## 5 Discussion  
As demonstrated, geophysical methods provided an overall view of the area, but could not identify pollutants in groundwater or soils. On the other hand, hydrochemistry data could identify the pollutants present in the area. Before going into a more detailed discussion, it must be noted that the two methods were not used simultaneously and, hence, cannot be compared for the same fieldwork timeframe. Therefore, the discussion will be focused on temporal (multiannual) trends. It must also be noted, that, over the period under investigation, chemical plants changed production operations, while others closed down or started operations. Furthermore, analysis of contamination by organic material and by farming activities was not included because temporal data of these contaminants were not available. Bearing in mind these points, it is clear that, according to the results obtained by both methodologies, ICCE activities have had a strong influence on the groundwater quality and have contributed to its degradation, as shown by both geophysical maps (Figures 4 and 6; Table 1) and hydrochemical data (Figures 5 and 9; Table 2). Data from the pre-remediation period (before 2003-2005) showed lower levels of groundwater contamination, as revealed by smaller areas of higher conductivity in Figure 4, and some regression in contamination in some flow paths, but also a steady expansion of contamination in other paths (Table 1). From 2001 to 2007, groundwater contamination peaked, as demonstrated by the larger high conductivity areas in Figure 4 and the increase in contamination velocity in Table 1, which was mainly due to higher concentrations of Cl, SO4, Na, and Fe (Figure 9 and Table 2). During this period, the increase in concentrations may be explained by the remobilization of highly contaminated waste and soils when the sealed landfill was constructed and then filled. After this period, data from Figures 4-6 and Figure 9, as well as Tables 1 and 2, show that contamination attenuated over time and some shifting in space occurred with groundwater flow. In addition, some hotspots showed a spatial distribution (Figure 5) linked to the old, but still operating drainage effluent systems (ditches and underground pipes) used by the ICCE. In conclusion, geophysics delivered an overall qualitative picture of the region, while hydrochemistry allowed for the qualification of the contaminant species. Furthermore, geophysical data provided information on the contamination spread velocity and paths,as well as on the effectiveness of remediation works and the impacts caused by wastes remobilization. Both methods allowed for the division of contamination characteristics in three periods: pre-remediation, the critical period while remediation works were implemented, and the post-remediation period. Some hotspots were identified, even in the 2016 campaign, pointing to new contamination sources associated with old effluent drainage systems that must be monitored and possibly repaired to stem the migration of contaminants. Therefore, this combined methodology proved suitable in order to provide key information to stakeholders, technicians, and authorities on the evaluation and remediation operations carried out and those yet to be implemented. Finally, even if the methods are not applied simultaneously, it is clear that the methodology proved to be effective, fast, and reliable to predetermine location sampling points, and, thus, has a general applicability that extends beyond this case study. Conceptualisation: M.S.M., C.P. and E.F.d.S. ; geochemical sampling campaigns: C.P., E.F.d.S., T.M. and N.D.; geophysical campaigns: M.S.M. and T.M. ; hydrothermal analysis: C.P., E.F.d.S. and N.D.; geophysical data processing: M.S.M. and T.M. ; writing--original draft preparation: C.P., M.S.M. and N.D.; writing--review and editing: M.S.M., N.D., C.P. and E.F.d.S. All authors have read and agreed to the published version of the manuscript.