NON-AQUEOUS-PHASE FLUIDS IN HETEROGENEOUS AQUIFERS - EXPERIMENTAL-STUDY

Understanding of flow and entrapment of non-aqueous-phase liquids (NAP Ls) in aquifers contaminated with organic chemicals is important in th e effective design of recovery and remediation schemes. Soil heterogen eities play a significant role in the physical behavior of these chemi cals. An experimental facility consisting of a large soil tank (lysime ter) and a dual-gamma spectroscopy system for fluid saturation measure ments was developed to simulate and monitor plume migration in water-t able aquifers after chemical spills. Experimental techniques and resul ts from a preliminary set of experiments conducted in unsaturated and saturated soils under homogeneous and heterogeneous conditions are pre sented. The effects of the layered homogeneities were pronounced in mo difying the migration pattern and velocity of the plume. Pockets of co arse sand placed across the path of the plume resulted in the soil act ing as a light NAPL trap. A fine-sand pocket acted as a barrier. Quali tative and quantitative data generated in the type of experiments pres ented in this paper can be used to validate multiphase flow models.