Laboratory Study of Immiscible Contaminant Flow in Unsaturated Layered Sands

Abstract

Little quantitative experimental data are available describing the behavior of immiscible contaminants in unsaturated heterogeneous porous media. Such data are, however, essential to the fundamental understanding of the processes governing nonaqueous phase liquid behavior and for the validation of modeling tools. The effect of macro-heterogeneity on light nonaqueous phase liquid (LNAPL) fl ow and distribution in the unsaturated zone was investigated experimentally by simulating LNAPL spills in layered soil systems consisting of sands with various textures. Two multiphase fl ow experiments were conducted in a twodimensional fl ume (180 × 120 × 8 cm). The vertical distribution of water and LNAPL pressure were measured using hydrophilic and hydrophobic tensiometers. An image analysis technique was used to estimate the saturation distribution of the fl uids in a two-dimensional vertical plane. The experiments show that LNAPL entrapment, which contributes to long-term soil and water contamination, depends strongly on the initial water saturation and water pressure at the layer interfaces and on the texture contrasts between the soil layers, which lead to permeability and capillary barrier effects. Thus, the knowledge of the initial water pressure and saturation distribution in unsaturated layered soil formations is critical to the correct prediction of LNAPL infi ltration and drainage.

Image analysis method for the measurement of water saturation in a two-dimensional experimental flow tank

“…Hence, this method allows for the measurement of the degree of saturation of two fluids in a three-phase system (Flores et al, 2011;Kechavarzi et al, 2005;Kechavarzi et al, 2008).…”

Generating Reproducible Microscale Heterogeneity for Transmitted‐Light Flow Visualization Experiments

“…It is important to recognize that the TLM differs from other near‐two‐dimensional experimental methods that typically use thicker samples and rely on other techniques for observing flow and transport processes and state variables (e.g., pressure and saturation), including direct emplacement of sensors (e.g., DiCarlo et al, 1997; Kechavarzi et al, 2008), visual observations on the outside of clear tanks (Hill and Parlange, 1972; Glass et al, 1989a,b), γ and X‐ray techniques (Stillwater and Klute, 1988; Oostrom et al, 1995; Tidwell and Glass, 1994; DiCarlo et al, 1997), light reflection methods (Van Geel and Sykes, 1997; O'Carroll et al, 2004), and multispectral image analysis (e.g., Kechavarzi et al, 2000, 2008). Many of these other techniques are described in the review by Oostrom et al (2007).…”

Two-Dimensional Liquid Water Flow through Snow at the Plot Scale in Continental Snowpacks: Simulations and Field Data Comparisons

“…iTOUGH2 is a simulation-optimization framework for the TOUGH suite of numerical models that have been utilized and validated for a range of processes in porous media (e.g. Fujimaki et al, 2008;Hannon and Finsterle, 2018;Ho and Webb, 1998;Kechavarzi et al, 2008;Lippmann and Bodavarsson, 1983). For this study we used the equation of state module 9 (EOS9), applying Richards' equation (Richards, 1931) for the transport of liquid water only and does not consider energy transport (Pruess et al, 2012).…”