Capture and cleanup of a migrating VOC plume by the in-well vapor stripping: a sand tank experiment

The capture and removal of a continuously produced, migrating Volatile Organic Compound (VOC) plume are demonstrated in a sandbox model using the in-well vapor stripping system. The transport and removal processes are analyzed using a laboratory-scale aquifer setup and numerical modeling. The spatial and temporal concentration variations of three VOCs (trichloroethylene, toluene and chloroform) and one non-volatile tracer (potassium) were determined using eight quadruple-level samplers evenly positioned throughout the model aquifer. The electrical conductivity of the K+-spiked water was continuously monitored using electrodes placed near the 32 sampling points. Laboratory results were numerically reproduced using 3-D flow and transport modeling combined with VOC volatilization and removal. The experiment was designed such that it was possible to distinguish (downgradient) between two groundwater bodies; the upper that was captured by the stripping well, and the lower unaffected by the remediation system. Thereby, the primary factors of efficiency of this remediation technique were evaluated.