Date of Award

Spring 1999

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Civil Engineering - (Ph.D.)

Department

Civil and Environmental Engineering

First Advisor

Dorairaja Raghu

Second Advisor

William R. Spillers

Third Advisor

Jay N. Meegoda

Fourth Advisor

Manish Chandra Bhattacharjee

Fifth Advisor

William Librizzi

Abstract

The sites at which the development is hindered by real or perceived contamination are called as Brownfield sites. It is a common trend in industry to develop these types of sites with surface and peripheral containments. It might prove unwise to develop the sites in this manner from a long term perspective without considering the associated risk. Because of this, a model has been proposed for long term risk assessments of brownfield containments.

Objectives of this study were to develop a contaminant transport model for flow of contaminants towards the surface and peripheral containments inside the site, a model for flow of contaminants through the containments and calculate the risk using CaITOX model.The model consists of two parts i.e. flow of contaminants towards peripheral containments and surface containments. The flow of contaminants towards surface containments is based on a process based model and flow of contaminant towards surface containments is based on Richard's equation. The peripheral containment model was applied to three case histories. The risk was acceptable in one case, unacceptable in another case and on the borderline in the third case. Thus the model was able to project the risk towards long term scenario.

Flow of contaminants towards surface containments in the vadoze zone can be modeled by Richard's equation that is a nonlinear, transient, partial differential equation of parabolic type. The equation was solved using the finite difference technique. The surface containment model was applied to a fictitious site and to a real case involving hexavalent chromium contamination. The model was able to predict the flow of contaminants in the vadoze zone. Risk was calculated using CalTOX model with modified fugacity approach.

CaITOX model utilized for risk, in the original form utilizes only residential exposure scenarios and only for organic chemicals. This model was modified to incorporate industrial exposure factors and inorganic chemicals.

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