Transient numerical simulations were conducted with the STOMP (Subsurface Transport Over Multiple Phases) code to assess the predictability of light nonaqueous-phase liquid (LNAPL) movement in the vicinity of sloping textural interfaces (capillary barriers) for variable soil water contents. The code is a three-dimensional, three-phase, compositional engineering simulator for modeling flow, contaminant migration, and remediation technologies. Simulations were conducted using nonhysteretic van Genuchten and Brooks-Corey retention functions. Simulation results were compared to results from two-dimensional chamber experiments performed in a glass chamber (50 cm x 60 cm x 0.95 cm) using Soltrol® 220 as LNAPL and two grades of silica sand (12/20 and 30/40 sieve sizes) to generate fine-over-coarse sloping textural interfaces. Numerical simulator input parameters were previously determined in independent experiments. Results indicated good general agreement between model and experiments. Differences in results between simulations using different water retention functions are discussed for a range of soil water contents.
In support of ongoing efforts to remediate subsurface contamination by NAPLs, numerical tools have been developed to help plan remediation activities and assess the associated risks. Because of the inherent complexities of three-phase systems in porous media, numerical simulators are required to solve remediation problems. These simulators combine constitutive theories developed from laboratory-scale experiments, governing equations for subsurface flow and transport, site-specific hydrogeologic data, and remediation process descriptions to predict the performance of remediation technologies. Through their abilities to simulate complex subsurface flow processes, numerical simulators can be used to forecast the movement of contaminants, identify design parameters to inhibit the migration of contaminants, comparatively evaluate remediation technologies, and increase the efficiency of cleanup efforts by guiding remediation efforts. This poster paper demonstrates the application of the STOMP simulator to the prediction of LNAPL migration in a bedded porous media.
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White, M. D., M. Oostrom, M. H. Schroth, J. D. Istok and J. S. Selker. 1995. "Multiphase fluid flow in bedded porous media: 2. Numerical simulations." EOS, 76(45). American Geophysical Union Fall Meeting, San Francisco, California.