Electronic Theses and Dissertations

Date

2023

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Civil Engineering

Committee Chair

Brian Waldron

Committee Member

Scott Schoefernacker

Committee Member

Farhad Jazaei

Committee Member

Vivek Bedekar

Abstract

The primary aquifer supporting the municipal wellfield in Collierville, Tennessee, has been contaminated with trichloroethylene (TCE) and hexavalent chromium (Cr (VI)) since the 1970s and 1980s. Both plumes generated from industrial operations near the municipal wellfield are now under remediation though the cleanup goals have not been achieved yet. This study determines the contaminant transport parameter, longitudinal (α_L) and transverse dispersivities (α_T,α_V) in the aquifer using a simulation optimization-based approach. The contaminant transport model was simulated using MT3DMS using the outputs of a well-calibrated MODFLOW-NWT flow model. Transport models were most sensitive to source concentration and initial boundary conditions. The total simulation runtime was reduced 8-fold using the Python multiprocessing library. The optimum calibrated values for longitudinal dispersivity (α_L) in the aquifer range from 5.5 m at 80 to 86 m from source, to 20.5 m at a distance 950 m form source, while the transverse dispersivities range from 0.28 to 6.98 m for horizontal (α_T) and 0.03 to 0.10 m for vertical (α_V). This study proposes a fast and simplified approach to estimate all three dispersivity coefficients using a numerical model and quantifies the scale dependency of longitudinal dispersivity.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to ProQuest

Notes

Open Access

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