Application of the patented Idro Well System (IWS) to limit saltwater intrusion in a drinking water well in ??Reggio Calabria

Seawater intrusion (SWI) is one of the most challenging and widespread environmental problems that threaten the quality of groundwater resources. Over pumping due to population growth is among the main causes, along with relative sea level rise and the reduction of aquifer recharge due to climate change. In this thesis an innovative remediation technique against SWI is presented applied on a well located in Reggio Calabria (South Italy) that serves the local aqueduct and taps into a thick unconfined aquifer. The well, which is located 1940 m from the coastline and at the foot of the Aspromonte mountains, experienced a progressive salinization of abstracted water. This thesis describes the interventions that were implemented to address the salinization issue and achieve drinking water standards. A patented system called Idro Well System (IWS) was adopted to cement the annular space and the bottom of the well creating a low conductivity layer in order to avoid pumping from the deeper and more saline layers of the aquifer. The intervention was successful, reducing electrical conductivity from 3060 μS/cm to 594 μS/cm and chloride concentration from 958 mg/l to 53 mg/l. A step drawdown test demonstrated that cementing caused the reduction of hydraulic transmissivity due to a lower saturated thickness and that the improvement of the chemical parameters was not achieved at the expense of the hydraulic efficiency of the well. A 3D numerical groundwater flow model was developed with the finite-element code FEFLOW to identify the capture area of the well, demonstrating that recharge comes all from the mountains and not from the coastline. This result demonstrates that salinization issues were due to upconing from the deeper aquifer layers, but not to seawater intrusion from the coastline. This work represented a case study example of the measures that can be implemented to solve water salinization issues occurring in wells drilled into coastal aquifers, with several future applications.