Unlocking the full potential of low-flow sampling and purging activities through aquifer hydraulic conductivity estimation: Strengths and limitations

A novel approach has recently been proposed to investigate the use of steady-state groundwater levels in monitoring wells during low-flow purging and sampling (LFPS) to determine the aquifer hydraulic conductivity, typically estimated by slug test (ST) methods. Specifically, during the LFPS of monitoring wells, it is possible to use the collected drawdown data to estimate the horizontal hydraulic conductivity (KH). In this study, the results of KH estimations, given by both ST and LFPS methods, are presented for a small landfill site in central Italy, together with transient analyses on water level data collected during LFPS, carried out and added to the usual steady-state ones for the first time. The results obtained by LFPS showed a very high correlation with KH values obtained by KGS model interpretation of ST data. In addition, different flow models have been applied to the same measured data of LFPS, affecting results no more than a factor of three. These outcomes highlighted the great potential of low-flow purging data to estimate hydraulic conductivity. This procedure, taking advantage of routine groundwater quality monitoring operations, can provide stakeholders with a very large amount of quantitative data on aquifer conditions over time, reducing time and costs for site characterization, particularly in cases of potential contamination.