Correlation Between 1, 2 and 3-D LNAPL Migration Patterns at Equilibrium in Unsaturated and Saturated Sand

This paper presents results of an experimental investigation for Light Non-Aqutous Phase Liquids (LNAPLs) migration patterns in unsaturated and saturated sand. Field and 3-D experimental investigations for LNAPL migration in variably saturated soils are generally avoided because of limited resources, excessive time requirements, and potential adverse environmental effects at the site. With the objective of exploring patterns of LNAPL migration, an extensive experimental investigation was undertaken. The migration patterns of LNAPL obtained using 1-D (column), 2-D and 3-D tanks filled with unsaturated and saturated sand were critically examined to illustrate the salient features of major differences between various LNAPL patterns. Digital imaging was employed to record the advancing front of LNAPL during infiltration as well as the final distribution of LNAPL at equilibrium. The results suggest that 1-D column test results should be treated with caution because of the major implication of the boundary conditions. In addition, results of 2-D LNAPL migration pattern were found to be in good correlation with those obtained from 3-D tank. However, a scale factor should be applied on 2-D LNAPL distribution at equilibrium to account for the restriction of LNAPL migration in the third direction.