ORCID

0009-0004-6199-6160

Keywords

Coal Combustion Products (CCPs), Liner System Equivalency, Leachate Generation, Water Balance Cover, Numerical Simulation, Machine Learning

Abstract

Designing landfill containment systems that remain effective over decades to centuries poses significant challenges in geoenvironmental engineering, especially for landfills managing coal combustion products (CCPs) with complex hydraulic and chemical behaviors. This dissertation aims to develop an integrated, performance-based framework for evaluating landfill barrier systems by combining numerical modeling, experimental leaching tests, and machine learning prediction. The first component assesses the equivalency of the Florida double liner system relative to the Subtitle D composite liner mandated by the U.S. Environmental Protection Agency (US EPA). Using field leakage observations and COMSOL Multiphysics-based numerical simulations, results demonstrate that the Florida system, when properly constructed, can provide comparable or superior containment. The second component employs SEEP/W simulations to quantify long-term leachate generation in CCP landfills under varying climates, cover designs, and waste properties, which are then coupled with EPA Method 1314 column leaching data to estimate time-dependent release of trace elements such as arsenic, selenium, boron, and molybdenum. The third component evaluates the performance of evapotranspiration-based water balance covers in arid environments using the Teapot Dome landfill as a reference site. Simulations show that vegetated covers with woody shrubs and suitable soil profiles can maintain percolation below regulatory thresholds. Finally, a random forest regression model is developed to predict van Genuchten parameters (α and n) based on compacted soil index properties, providing an efficient and cost-effective alternative to laboratory testing for hydraulic input calibration. Overall, the study offers a comprehensive framework for assessing landfill containment system performance over time and under diverse field conditions. The findings support improved design, regulatory compliance, and post-closure care planning, while highlighting the value of integrating numerical tools, experimental data, and data-driven methods in advancing sustainable waste containment engineering.

Completion Date

2025

Semester

Summer

Committee Chair

Chen, Jiannan

Degree

Doctor of Philosophy (Ph.D.)

College

College of Engineering and Computer Science

Department

Department of Civil, Environmental and Construction Engineering

Format

PDF

Identifier

DP0029631

Language

English

Document Type

Thesis

Campus Location

Orlando (Main) Campus

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