Chapter 9 Subsurface Contaminant Transport

Abdel-Mohsen Onsy Mohamed
Evan K. Paleologos

Document Type

Book Chapter

Source of Publication

Fundamentals of Geoenvironmental Engineering

Publication Date

1-1-2018

Abstract

The mathematical description of groundwater flow, contaminant transport and diffusion through porous media, can be found in many textbooks devoted to the development of governing relationships and solution of the relationships subject to various initial and boundary conditions. The success of the mathematical modeling and the numerical analysis is highly dependent on the quality of the input data and the accuracy in the representation of the physical, chemical, and biological interactions with the transporting fluid and contaminants. In the absence of proper representation, model predication will continue to render unreliable results. Therefore, in this chapter we are concerned with the examination of contaminant transport from the viewpoint of how realistic the models are in representing the physical problem under investigation. The basic physical mechanisms by which miscible (soluble) and immiscible (nonsoluble) contaminants are transported in the subsurface environment were examined. Examples of various analytical models for column experiments, chemical spills, and chemical plumes from continuous releases of contaminants were discussed. In addition, the basic types of apparatus (rigid and flexible wall permeameters) used for the determination of hydraulic properties in laboratory testing were discussed. Experimental techniques (batch equilibrium and soil column leaching) used to determine the adsorption characteristics in the laboratory were examined. The laboratory methods (steady and transient states) used to estimate the transport parameters of chemical species diffusing through waste containment barriers were discussed. The common procedures used to calculate the transport parameters such as decreasing source concentration, time-lag method, and root time method were described and evaluated. The contaminant transport modeling of soluble and nonsalable contaminants using the second postulate of irreversible thermodynamics was presented. Finally, due to variability in parameters and variables in the governing transport equations, it becomes important to treat a variable (e.g., the head or the flux in groundwater flow problems, or the concentration in transport problems) not as a single deterministic solution, but into its mean, variance, and covariance function, or other high-order statistical moments. On that basis, the main issues in stochastic modeling of contaminant transport in soils were highlighted.

Publisher

Elsevier

Volume

Geophys. Res. Lett. 32 8 2005

First Page

283

Last Page

324

Disciplines

Environmental Engineering

Indexed in Scopus

no

Open Access

no

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