The value of online measurements to monitor and control a remediation process. Persistent arsenic (As) pollution sources from anthropogenic activities pose a serious threat to groundwater quality. This work aims to illustrate the application of an innovative remediation technology to remove As from a heavily contaminated fractured aquifer at a historically polluted industrial site. Groundwater circulation well (GCW) technology was tested to significantly increase and accelerate the mobilization and removal of As in the source area. The GCW extracts and re-injects groundwater at different depths of a vertical circulation well. By pumping out and reinjecting in different screen sections of the well, the resulting vertical hydraulic gradients create recirculation cells and affect and mobilize trapped contaminants that cannot be influenced by traditional pumping systems.