Combining continuous monitoring and High-Precision altitude measurements in forensic groundwater surveys. A case study of chlorinated solvent pollution in an urban context

This paper describes a forensic investigation of groundwater in an urban context in Italy. The present case study was conducted to detect the hydraulic flow path between a sportfishing pond and a nearby industrial plant’s contaminated groundwater site. The investigation was performed to evaluate the potential for diffusion of contaminants through groundwater flow into a fishing pond located downstream from a chemical factory. High-precision altitude measurements of monitoring stations combined with continuous water level monitoring were crucial to understand the groundwater flow dynamics and define the hydrogeological conceptual model. The study verified that the fishing pond, dug in low-permeability volcanic rock, was not hydraulically connected to the groundwater flow. The presence of contaminants in the pond may be related to the periodic topping-up activity performed using water from an existing well. The identified groundwater flow paths were consistent with the possible contaminant migration from the chemical factory to the water well near the fishing pond.