## 2 Materials and Methods  
At the contaminated site of the new high-speed railway station of Bologna, Italy, a large amount of slightly contaminated soil (\(\sim\)1,000,000 m\({}^{3}\)) was excavated to create the new underground station. The excavation activities for construction of the structure that houses the station involved the removal of land attributable to shallow and intermediate aquifers. Corresponding to the excavation, a bypass system equipped with activated carbons for the treatment of groundwater was implemented prior to our intervention. The management of a large amount of heterogeneous data supports the entire remediation project, from the characterization phase to the application of interventions [15]. A large amount of multithematic data was stored and centralized in an integrated information management and analysis platform. The integrated geodatabase represents an effective near-real-time decision support system (DSS) able to manage and release data during the different remediation phases, from characterization to technique implementation, in the field test and at full scale [26]. The hydrogeological model analysis and selection of a remediation technology utilized multiscale and multiphase approaches [32]. In the first phase, the main hydrogeological characteristics surrounding the new high-speed railway station at full scale were detected. In the second phase, starting from the hydrogeological conceptual model obtained from the first one, the analysis focused on the pilot test area, increasing the observation scale to analyze in more detail the effects of geological heterogeneity in the first intervention area. The advanced geological modeling at both scales followed the reworking of stratigraphic data and archiving them in the geodatabase. In the study area, 47 stratigraphic logs from boreholes drilled between 2005 and 2014 were available. A further 17 boreholes were drilled during our activity (2016), to refine the geological model and take soil samples for laboratory tests. Geological surveys and laboratory analyses identified the lithotechnical units and evaluated the permeability of the stratigraphic horizons present in the station subsoil [33]. For this work, the stratigraphic data were reinterpreted and homogenized for a hydrogeological perspective, i.e., the various stratigraphic levels were merged or differentiated according to grain size and, hence, permeability [34]. The subsoil geological structure was subdivided in accordance with the groundwater circulation scheme. Permeability was evaluated via small-scale in situ tests (5 Lefranc tests) as a function of particle size, and through permeability tests in triaxial cells. Twenty-one soil samples were collected to perform particle size tests [35], determine Atterberg limits [36], and assess water content [37]. These analyses were performed at the Applied Geology Laboratory of the University of Rome (La Sapienza). The data acquired were organized according to a hydrostratigraphic criterion [34]. The georeferencing of the previous data and the new periodic measurements allowed hydrogeological structure modeling and reconstruction of the groundwater circulation scheme. The evaluation of hydrodynamic parameters enabled us to quantify the velocity of groundwater flow [38]. The hydrogeological setting was assembled based on a piezometric network consisting of 61 measurement points, 29 and 32 piezometers intercepting the shallow and intermediate aquifers, respectively, were considered. To strengthen the geological model, which arose from the interpolation of punctual data, geophysical investigations were conducted by performing three ERT [39] profiles covering the pilot test area. The ERT profile acquisition was aimed at refining the conceptual geological model in the first application area. The site imposed significant logistic limitations. Giventhe presence of the nearby railroad in the west and construction works in the east, it was possible to deploy lines having sufficient length only in the north-south direction.