Environmental Engineering

Program Overview

Quoc P. Nguyen (quoc_p_nguyen@mail.utexas.edu) is the Program Manager of the Environmental Engineering research program. The primary purpose of the Environmental Engineering Program is to provide short-term and long-term cost-effective solutions to challenging subsurface environmental problems faced by industrial and governmental groups. Research in subsurface environmental engineering is directed toward both the characterization and remediation of contaminated aquifers. These research projects range from the fundamental investigation of the transport of chemicals and microbes in permeable media using advanced techniques such as magnetic resonance imaging to applied projects up to and including pilot field tests of several technologies.

Research Projects

Nicolas Espinoza

CO2 geological storage can help mitigate the emission of greenhouse gases to the atmosphere. Large-scale implementation of CO2 geological storage requires full understanding of the interaction between injected CO2, host pore fluid, and rock minerals.

Steven L. Bryant

Contamination of groundwater by NAPLs is a widespread problem. Typically, however, the location of NAPL contaminant sources is very poorly known, and characterization of a site is expensive. Design of remediation projects is greatly compromised by this uncertainty. For example, a scheme designed to remove uniformly distributed low saturations of NAPL may be very inefficient if the NAPL is concentrated in a few regions of high saturation.

Gary A. Pope, Mojdeh Delshad

The objective of this research is to develop and apply a three-dimensional, multiphase, multicomponent model capable of simulating the fate and transport of nonaqueous liquids (NAPLS) in the saturated and unsaturated zones of confined and unconfined aquifers. The model is capable of simulating multiple solids and fluid phases under realistic aquifer conditions and transformation of both organic and microbiological species. Some of the specific objectives of this research are:
 

Gary A. Pope, Russell T. Johns

In-Situ Thermal Desorption (ISTD) is a soil heating remediation technology currently applied primarily to remove organic contaminants from the vadose zone. It has been shown to be effective in the clean up of a wide range of contaminants from volatile organics to heavy oils.

 

Steven L. Bryant, Gary A. Pope

Funding source: Advanced Technology Program (State of Texas)

Funding amount: $150,000 for the period of January 2004 - December 2006

Geological sequestration is one way greenhouse gases can be mitigated in sufficient volumes. This project focuses on obtaining quantitative assessments of the potential for permanent geological sequestration of carbon dioxide in aquifers.

Matt Balhoff

Carbon sequestration, a potential solution for mitigating climate change, is inherently a multiscale process because transport mechanisms range from the nanometer scale to the kilometer scale. In carbon sequestration, CO2 is captured from emission gases as an industrial byproduct and then injected into potential storage sites for long-time storage.

Larry N. Britton

Widespread use of degreasing solvents like tetrachloroethene (PCE) and trichloroethene (TCE) has left a legacy of subsurface contamination. One of the strategies for remediation of contaminated sites is biological reductive dehalogenation whereby soil microorganisms sequentially remove chlorine atoms from the compounds in a reductive pathway under anaerobic conditions. However, in heavily contaminated source zones the rates of biological dehalogenation often are nil because of inhibitory effects.

David DiCarlo

Understanding the dynamics of three-phase flow is essential for optimizing enhanced oil recovery and vadose zone remediation processes. The ultimate recovery of oil and other non-aqueous phase liquids (NAPLs) depends on the residual saturations and relative permeabilites of each of the phases. In particular, the wettability of the porous media affects the placement of the fluids in the porous media and the relative permeabilities.

Other Research

Principal Investigators: Mojdeh Delshad and Gary A. Pope

Abstract

Chlorinated solvents known as dense non-aqueous phase liquids (DNAPLs) are one of the most serious groundwater contamination problems in the U.S. Surfactant enhanced aquifer remediation has emerged in recent years as the best available technology for remediating groundwater contaminated by chlorinated solvents. Accurate flow and transport modeling with the University of Texas chemical flooding simulator, UTCHEM, has played a critical role in the understanding of surfactant remediation and its efficient and reliable use to clean up superfund sites.

Russell T. Johns, Larry W. Lake

Accidental release of petroleum hydrocarbons to the subsurface may occur through spills around refineries, leaking pipelines, storage tanks or other sources. If the spill is large, the hydrocarbon liquids may eventually reach a water table and spread laterally in a pancake-like lens. Hydrocarbons in the aquifer that exist as a separate phase are termed free product or light nonaqueous phase liquids (LNAPL).

Related Research

Research Initiatives

Public Abstract

We have developed and implemented a multiphase and multicomponent dual porosity model in a 3-D flow and transport numerical model called UTCHEM in order to evaluate the potential of current characterization and remediation technologies of nonaqueous phase liquids (NAPLs) in fractured porous media. Many natural porous media are fractured and some contain NAPL contamination. For example, the Bear Creek Burial Grounds at Oak Ridge Laboratory and the Test Area North at Idaho National Laboratory are sites with fractured media contaminated by dense NAPLs.

Abstract

Field observations of anomalously fast migration of chemical species have presented regulators and researchers with a paradox. Many hazardous chemical species adsorb very strongly to mineral surfaces and should therefore migrate very slowly if released into the subsurface. Yet travel speeds approaching groundwater velocity -- orders of magnitude larger than expected -- have been observed. As emphasized in a recent report by the National Research Council, these observations reveal shortcomings in our understanding of contaminant fate and migration in the subsurface.