Centrifuge modeling of light nonaqueous phase liquids transport in unsaturated soils

Centrifuge modeling appears useful for studying geo-environmental problems such as pollutant migration in subsurface systems. In this study, centrifuge tests were conducted to simulate a gasoline spill from a leaking underground storage tank (UST) and the subsequent subsurface migration of the gasoline. When the centrifugal acceleration reached the desired g level, the gasoline was released from the UST and then it migrated in the unsaturated soil for a prototype time equivalent to 1 year. After the centrifuge tests, soil samples were collected using sampling tubes and the concentrations of individual constituents in the light nonaqueous phase liquids (LNAPLs) were directly measured by means of gas chromatograph analysis. Two types of unsaturated soils were used to study the migration patterns of LNAPLs in unsaturated porous media. Centrifuge test data show that the migration pattern of LNAPLs is related to the soil type and the physical properties of individual constituents in the LNAPLs.