Department of Civil and Environmental Engineering
B.A.Sc. (University of Ottawa) 1994
M.S. (Clarkson University) 1997
Ph.D. (University of Michigan) 2004
Dr. O’Carroll’s research interests lie in the general area of groundwater contamination and remediation. He is particularly interested in the development of
innovative groundwater remediation technologies, improving our understanding of the phenomena that govern contaminant fluid flow in the subsurface and the
utility of nanomaterials in environmental engineering.
The development of innovative remediation technologies for subsurface nonaqueous phase liquids (NAPL) remediation is one of the focuses of Dr. O’Carroll’s research group. He is currently developing two remediation technologies, hot water flooding and remediation using nanotechnology. Hot water flooding exploits the temperature dependence of fluid properties, such as viscosity and interfacial tension, to improve removal efficiencies of viscous NAPLs. To do this hot water is pumped into the contaminated subsurface, heating up the surrounding soils and NAPL waste and reducing the pressure needed for water to push NAPL out of the pore space where it can be collected in an extraction well. Improved NAPL removal efficiencies result in less subsurface NAPL mass available to act as a long-term source of groundwater contamination. This technology has been used in the petroleum industry for petroleum recovery from subsurface reservoirs but conditions in the contaminated subsurface differ substantially from those in petroleum reservoirs. Dr. O’Carroll’s work suggests that hot water flooding technology has the potential to significantly facilitate the remediation of viscous NAPLs in the contaminated subsurface. Nanomaterials are receiving widespread interest in a variety of fields due to their unique, beneficial chemical, physical, and mechanical properties. In the environmental engineering community there is considerable interest in pumping nanomaterials into the ground where they can flow with groundwater to a contaminated region and convert hazardous chemicals (ie. chlorinated solvents) into benign daughter products (ie. ethane, butane). Dr. O’Carroll’s research team is focusing on the use of nanomaterials for the subsurface remediation of NAPLs. His work suggests that nanomaterials have tremendous potential for subsurface remediation.
Dr. O’Carroll has also made significant contributions in understanding the migration, entrapment and remediation of complex NAPLs in the subsurface. To date much of the research has focused on pure fluids and ideal water-wet porous media. At most sites worldwide, however, NAPLs were not disposed of as pure liquids, but in acidic or basic mixtures often containing surface active compounds. These mixtures can alter the wettability of subsurface porous media. In addition natural materials have a variety of wetting characteristics. Dr. O’Carroll’s work shows that the behavior of complex NAPLs in the subsurface differs significantly than that of pure NAPLs. Failure to account for this non-ideal behavior can significantly impact predictions of complex NAPL migration, entrapment and remediation.
Dr. O’Carroll is also actively developing computer models to delineate the extent of NAPL contamination and to conduct feasibility studies for the determination of appropriate NAPL remedial alternatives. At present it is not possible to predict the extent of NAPL contamination in the field with great certainty in part due to shortcomings in multiphase flow numerical models. Dr. O’Carroll is currently investigating the utility of alternative governing equations in multiphase flow simulators. He has found that the inclusion of dynamic effects in capillary pressure in multiphase flow numerical simulators can significantly improve agreement between experimental observations and model predictions. This new computer model has the potential to significantly improve the prediction of NAPL migration, entrapment and remediation at the field scale.
KEYWORDS: multiphase flow; geoenvironmental engineering; environmental engineering; chlorinated solvents; carbon nanotubes; remediation; modeling; nanoparticles; nanomaterials.