Research interests are in hydrogeology and engineering. Dissertation dealt with arsenic transport in gold mine heap leach and waste rock impoundments. This work was split into two phases: laboratory determination of the pH-dependent sorption behavior of As(III) and As(V) on two examples of gold ore, and the development of an unsaturated reactive transport code to include the experimental observations and to provide a means of estimating arsenic flux from mine waste rock and heap leach dumps. This work resulted in a new isotherm formulation that includes pH dependence, and modifications to enable reactive transport of arsenic to an existing unsaturated transport code from the U.S. Soil Salinity Laboratory through collaboration with J. Simunek and R. van Genuchten. A significant finding from this work is that there is a distinct decoupling between the flow physics and arsenic geochemistry such that covering spent heaps and waste rock dumps with an engineered earthen cover will have no impact on reducing the concentration of arsenic in the water produced at the bottom of these structures. Current research projects include: developing a reactive transport version of a DSC flow model for the Nevada Test Site, evaluating the thermodynamic database developed for the application of surface complexation models to radionuclide adsorption, extending the surface complexation modeling database for radionuclide analog sorption onto oxide and silicate minerals to high temperatures, developing a down-borehole tritium detector, examining the gas and leachate geochemistry of municipal waste landfills, and continuing the development of the arsenic reactive transport model in mine heap leach systems and in natural porous media environments.