FATE AND TRANSPORT OF PATHOGENS IN A FRACTURED AQUIFER IN THE SALENTO AREA, ITALY

This study investigates the fate and transport of pathogens introduced by artificial groundwater recharge at the Nardo` fractured aquifer in the Salento area, Italy. Wastewater effluents from a municipal treatment plant with known pathogen concentrations were injected into a sinkhole and the migration of pathogens in the fractured aquifer was monitored at six sampling wells. The fate of pathogens was quantified by a mathematical model describing colloid transport in a set of three-dimensional, parallel fractures with spatially variable aperture. The number of parallel fractures and their average fracture aperture were determined from appropriate field pumping and tracer tests. The aperture spatial distribution was described by an experimental semivariogram developed from available field data obtained from two tracer tests and 34 pumping tests. The experimental results suggest that for the municipal wastewater injected into the Nardo` aquifer the required most conservative set back distance for drinking wells should be over 8000 m.