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Design Analysis of Sequential Ex-Situ Remediation
of Contaminated Soil
Fehmidakhatun A. Mesania and Aaron A. Jennings
Abstract
Terrestrial remediation is the most common form of remediation. It is more common then atmospheric or aquatic system remediation because the contaminants tend to be less mobile and are contained in a smaller volume. However, the technical problems of terrestrial remediation are still substantial. We are just beginning to evolve what started as ad-hoc field practice into mature engineering approaches. Of the available options for terrestrial remediation, recent efforts have concentrated on in-situ processes because of perceived faults in ex-situ approaches. However, when properly designed and monitored, ex-situ remediation can yield superior results to soil contamination problems. This is particularly true for sites characterized by small amount of petroleum contaminated soil from sources such as of underground storage tank leaks or surface spills. The environmental mobility of products such as gasoline, leaks and spills pose serious threats, especially to nearby groundwater resources.
The main objective of this study is to develop a remediation analysis
tool that will allow engineers to consider the potential merits of a sequence
of remedial actions applied ex-situ, at low cost and under controlled conditions,
to a contaminated soil. The design analysis package will be constructed
by using a backbone simulation engine that can interface with a large set
of remediation process subprograms. The simulation engine will define the
structure of the problem and the remedial process subprograms will implement
individual treatment options such as: bio-venting, soil washing, bioremediation,
vapor extraction, etc., based on existing practical model expressions.
The concept is simple. Contaminated soil will be excavated and delivered
to an acceptable treatment site where it is constructed into a pile. Once
the pile has been constructed and encapsulated, the soil would be treated
with a sequence of conventional treatment processes. The software package
will help engineers consider various combinations of process sequences
and process operation to achieve the desired remediation goals at low cost.
Figure 1: Contour Plots from a problem with non-dimensional sinks and sources
applied at several boundary segments.
Figure 2 : Velocity vector field for potential field illustrated
above
Figure 3 : Convective, dispersive, mass transport model for a single conservative solute at Time=0.5 day and Time=1.0day, respectively.
CWRU Department of Civil Engineering
Communication