Numerical groundwater flow modelling for remediation design and seawater intrusion assessment at a coastal industrial site

A three-dimensional density-dependent groundwater flow and transport numerical model was implemented using the finite element code FEFLOW, to assess jointly seawater intrusion and the remediation strategy at a former gas plant site located along the coastline in southern Italy. The aim of the remediation project was to contain contaminated groundwater (contamination by arsenic and total petroleum hydrocarbons) movements out of the site, while avoiding seawater intrusion inland. The model demonstrated that installing a physical groundwater flow barrier would actually increase seawater intrusion at the site, and that the hest remedial solution would be a coupled pumping injection barrier. In fact, this remediation strategy would allow for effective containment of contaminated groundwater, while at the same time reducing seawater intrusion into the freshwater aquifer.