ABSTRACT:

Numerical models have been developed by past researchers to simulate the migration of light nonaqueous-phase liquids (LNAPLÕs) in porous media. The purpose of this research was to conduct physical experiments to provide quantitative data needed for validation of such numerical models. The scenario modelled for this research was the infiltration of Soltrol-130 (LNAPL) into the vadose zone of a 30/50 silica sand. The physical modelling consisted of monitoring infiltration of LNAPL into a 1.2 m by 1.2Êm by 0.10 m tank filled with the sand. The sand tank was designed to represent a twodimensional profile model. Water saturations and water and Soltrol-130 pressures were measured in the tank using resistivity probes and tensiometers, respectively. Physical properties such as capillary pressure-saturation curves, the soil saturation-resistivity relationship, and soil permeability were determined for the soil and fluids used.

INTRODUCTION

The preliminary stages of subsurface contamination by a light nonaqueous-phase liquid (LNAPL) involves multi-phase flow of LNAPL, water and air phases in a porous medium. Numerical models have been developed by many researchers to predict LNAPL transport and distribution (Kueper and Friend, 1991, a,b; Huyakorn et al., 1994). These numerical models are quite complex and have not been thoroughly verified using experimental data sets. Several researchers have used physical models to experimentally observe multi-phase fluid flow on a macro scale (Pantazidou, 1991; Graham et al, 1992; Lenhard et al, 1993, Van Geel and Sykes, 1994; and Chevalier, 1998). The focus of these experimental studies has been to obtain quantitative measurements from controlled physical experiments. The objective of this paper is to report on physical modelling at the macro scale and to provide further quantitative data for verification of numerical models. To achieve this objective, physical modelling of two-dimensional, transient, LNAPL plume migration was performed in a sand tank.

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