HR: 13:40h
AN: H43H-01 INVITED     [Abstracts]
TI: Effects of Aquifer Heterogeneity on Mass Flux Emission From DNAPL Entrapment Zones
AU: * Illangasekare, T H
EM: tissa@mines.edu
AF: Center for Experimental Study of Subsurface Environmental Processes (CESEP), Colorado School of Mines 1600 Illinois St., Golden, CO 80401-1887 United States
AU: Saenton, S
EM: ssaenton@mines.edu
AF: Center for Experimental Study of Subsurface Environmental Processes (CESEP), Colorado School of Mines 1600 Illinois St., Golden, CO 80401-1887 United States
AU: Kim, Y
EM: ykim@mines.edu
AF: Center for Experimental Study of Subsurface Environmental Processes (CESEP), Colorado School of Mines 1600 Illinois St., Golden, CO 80401-1887 United States
AU: Rodriguez, D
EM: drrodrig@mines.edu
AF: Center for Experimental Study of Subsurface Environmental Processes (CESEP), Colorado School of Mines 1600 Illinois St., Golden, CO 80401-1887 United States
AB: Organic waste products that are in the form of dense non-aqueous phase liquids (DNAPLs) exhibit complex flow and entrapment behavior in the subsurface. Heterogeneity at different scales from pore to macro-scale in combination with flow instabilities controls the fluid flow behavior and hence the final entrapment architecture. Two primary mechanisms contribute to mass flux emission from source zones where DNAPLs are entrapped. The first is the result of the soluble constituents of the DNAPL dissolving into the flowing groundwater through mass transfer that occurs at DNAPL-water interfaces in residual zones and pools. The relationships of mass flux generation to entrapped mass from residual zones where NAPLs exit in the from of ganglia or residuals and from pools where the saturation varies from high to low values are different due to the differences in the contact morphologies between the flowing aqueous phase and entrapped DNAPL. The second process that contributes to emission is a result of rebounding of dissolved mass that has diffused into the low permeability zones of the aquifer during active DNAPL dissolution. Aquifer heterogeneity that controls the NAPL entrapment and groundwater flow plays a critical role in the generation of mass flux through both these mechanisms. The relationships between the DNAPL mass in the source zone and dissolved mass emission need to be understood and quantified to evaluate the benefits of partial mass removal from source zones during remediation. Methodologies for up-scaling the mass transfer from laboratory to field scale that take into consideration effects of heterogeneity are in their early stages of development. Experimental investigations conducted in intermediate-scale test tanks packed to represent various degrees of heterogeneity that produce different entrapment morphologies and architecture are used to obtain an insight into mass transfer processes. An up-scaling methodology for mass transfer that uses stochastic parameters of the heterogeneity field and parameters that define the entrapment architecture is developed. The data generated in the intermediate-scale test tanks are used to validate this up-scaling methodology.
UR: http://cesep.mines.edu
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
DE: 1869 Stochastic processes
DE: 1894 Instruments and techniques
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting