| This study seeks to investigate a problem of predicting the hydraulic conductivity of NAPLs in partially saturated soils and to relate the hydraulic conductivity to basic soil parameters that are either easy to determine or are in wide use. To evaluate hydraulic conductivity in partially saturated soils, previous researchers have focused on flow geometry, soil and chemical properties, etc. used in CHEMFLO program by Nofziger et al., (1989) and saturation equations by such authors as Van Genutchen (1980) and Brooks and Corey (1964). Among those, the soil-water characteristic curve (SWCC) is the most widely used constitutive relations for unsaturated soils (Claudia, et al. 2000). It uses matric suction to relate to fluid flow characteristics of unsaturated soils. However, the authors concluded that even the most experienced researchers have difficulties in getting a unique SWCC for a soil and that soil suction and SWCCs cannot be simply measured with great precision at the present time. Hillel (1998) stated that there is as yet no universally accepted method available to predict unsaturated hydraulic conductivity from more easily obtainable soil properties.;The approach used in this research includes the development of a new test instrumentation procedure. This study developed a new laboratory based method for solving the problem. It uses easy to obtain soil properties. The properties used are water content, NAPL content, void ratio and soil suction. The test data were used to determine the unsaturated hydraulic conductivity of a chosen NAPL by using nonlinear regression analysis. The method could be used with both DNAPLs and LNAPLs such as gasoline.;The benefits of this study include (1) establishing previously unknown relationships between unsaturated hydraulic conductivity and basic soil properties such as water content, NAPL content, void ratio or porosity, matric suction, and soil unit weight; (2) providing a new tool for predicting the fate and transport of DNAPL or LNAPL in the vadose zone; and (3) predicting the contamination potential of NAPL/LNAPL. |
