Bench-scale Investigations on Vibratory Mobilization of Immiscible Liquid Ganglia

Prior investigations by the principal author evaluated the feasibility of mobilizing non-aqueous phase liquid (NAPL) ganglia by inducing vibrations in a soil-NAPL-water medium. In this paper, results from bench-scale experiments are reported to provide a practical understanding of the impact of vibrations (induced with a probe-type vibrator) on relative density of the medium and on the ganglia concentrations. It is shown that the variation of ganglia concentrations in the vibrated zone are governed not only by the relative density variation but also by the uniformity of flow gradients. Non-uniform flow rates in the zone around the vibrator may result in clean-up of some areas and in accumulation of ganglia (exceeding initial residual volumes) in other areas. The results from the experiments support an integrated approach where the vibrator is augmented with a pumping mechanism yielding uniform and predictable flow gradients in the vibrated zone.