UNIVERSITY OF COLORADO AT DENVER

PLACE: Mathematics Conference Room 626 UCD Building, 1250 14th St., Denver

TIME: NOON (Refreshments served at 11:45 am)

DATE: Oct. 16, 2000

Title:  Mathematical Modeling of the Migration and Recovery of Dense Nonaqueous Phase Liquid Contaminants in the Subsurface

Speaker:
Linda M. Abriola
Environmental and Water Resources Engineering
The University of Michigan
Ann Arbor, MI


Abstract:
This presentation provides an overview of research focused on the development 
and application of multiphase flow and transport models for the prediction 
of organic liquid contaminant migration and recovery in heterogeneous 
porous media.  One remedial technology, surfactant enhanced aquifer 
remediation, is highlighted.  Experimentally-based mathematical models 
are evaluated in terms of their ability to predict observations from a 
series of laboratory sand box experiments.  To simulate subsurface 
heterogeneity, the two-dimensional boxes were packed with distinct layers 
of various well-characterized sandy porous media.  Tetrachloroethylene 
(PCE) was introduced to these aqueous phase-saturated media at a constant 
infiltration rate and allowed to redistribute.  Subsequent flushing by a 
nonionic surfactant solution was used in some experiments to examine 
remedial performance.  Experimental observations indicate that both 
rate-limited solubilization and soil texture variations reduced PCE recovery 
to levels below those anticipated from batch and column measurements, and 
that interfacial tension reductions can have a marked influence on PCE 
distribution.  Although predicted migration, entrapment, and recovery agreed 
reasonably well with experimental observations, example simulations highlight 
the extreme sensitivity of model predictions to grid resolution and subsurface 
heterogeneity.  The potential application of such state-of-the-art 
process-based models to field scale scenarios is assessed in view of 
these results.