HR: 08:15h
AN: H21H-02    [Abstracts]
TI: Validating a Multiphase Flow Numerical Model for DNAPL Migration in Two-Dimensional Heterogeneous Porous Media
AU: Gerhard, J I
EM: j.gerhard@ed.ac.uk
AF: Institute for Infrastructure and Environment The Univeristy of Edinburgh, Alexander Graham Berll Building The King's Buildings, Edinburgh, EH9 3JL United Kingdom
AU: * Grant, G P
EM: g.p.grant@sms.ed.ac.uk
AF: Institute for Infrastructure and Environment The Univeristy of Edinburgh, Alexander Graham Berll Building The King's Buildings, Edinburgh, EH9 3JL United Kingdom
AU: Kueper, B H
EM: kueper@civil.queensu.ca
AF: The Department of Civil Engineering Queen's University at Kingston, Ellis Hall, Kingston, ON K7L 3N6 Canada
AB: Following a dense, nonaqueous phase liquid (DNAPL) release to the subsurface, little is known about the rate of DNAPL migration and the time required for its eventual immobilization. Numerical simulations can fill this knowledge gap on the condition that the employed models are sufficiently validated; however, to date, validation for transient DNAPL migration has been limited to one-dimensional homogenous systems (Gerhard and Kueper, 2003). This research focuses on spatially and temporally validating the multiphase numerical model DNAPL-3D (and its associated constitutive relationships) for the infiltration, redistribution, and immobilization of a transient, fixed-volume DNAPL release in two-dimensional heterogeneous porous media. For this purpose, a two-dimensional bench scale experiment was conducted involving the release of 1,2-dichloroethane into an initially water saturated, spatially correlated, randomly heterogeneous sand pack. An image capture and analysis system permitted digital tracking of the evolving DNAPL body until migration ceased. The porous media employed in the bench scale experiment consisted of six, single mesh size sand types for which hysteretic nonwetting phase (NWP) relative permeability-saturation (krN-S) relationships were independently measured at the local scale. The local scale experiments revealed a correlation between porous media mean grain diameter and the maximum value of NWP relative permeability. Predictions of the bench scale experiment with DNAPL-3D were successful in reproducing the observed, complex DNAPL release in both space and time without any model calibration. The simulations revealed that model validation is only possible when the correlation of krN-S relationships to porous media type is accounted for in the formulation of the numerical model. Field scale simulations indicate that both the volume of porous media invaded by NWP, and the time required for NWP migration to cease, will be under predicted if correlation of krN-S to sand type is not accounted for. The simulation results suggest that the degree of this under prediction is increased as the mean intrinsic permeability of the release location decreases.
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1847 Modeling
SC: Hydrology [H]
MN: Fall Meeting 2005