My Master's work centered on the creation of realistic numerical models
for vaporous contaminant transport in soil. Since nonaqueous-phase liquids
(NAPLs) are often present in soil, one cannot justify a simple (linear)
retardation coefficient for volatile organic compound movement in the vapor
phase. Rather, one must explicitly calculate the phase partitioning via
Raoult's or Henry's Laws. The resulting 2-D and 3-D models (VENT2D and
VENT3D) are perfectly suited to modeling soil vapor extraction (SVE) as
a means of remediating contaminated soil. Since VENT3D was coded and debugged
last summer, I am making VENT2D available to the general public free
of charge. A VENT2D
FTP site contains all of the necessary files and an introduction to
the model. You can read some of the theoretical details in these:
Benson, D. A., A Two-Dimensional, Finite-Difference Model of the Phase Distribution and Vapor
Transport of Multiple Compounds, Unpublished Master's Thesis,
San Diego State Univ., 1992.(593 Kb pdf file)
Benson, D.A., D. Huntley, and P.C. Johnson, Modeling vapor extraction and
general transport in the presence of NAPL mixtures and nonideal conditions, Ground Water,
31(3), 437, 1993. See also a corrected figure and a comment and reply in Ground Water,
31(5), 857, 1993 and Ground Water, 32(1), pp. 146 - 150, 1994.
VENT3D is a fast, 3-D vapor transport model with NAPL partitioning that
uses a third-order transport algorithm with gradient checking for sharp
fronts. You can download a reduced-size
VENT3D demo here. After trying VENT2D and the VENT3D demo, get
a mini-brochure and order form.
David Benson
Desert Research Institute
Water Resources Center
2215 Raggio Parkway
Reno, NV 89512-1095
(702) 673-7496