Subsurface Source Generation and Transport from Spills of Alcohol Blended Fuels

The goal of this research is to improve the current understanding of the physical-chemical impacts of alcohol in an alcohol-blended fuel on the distribution and transport characteristics of alcohol and non-aqueous phase liquid (NAPL) contaminants from fuel releases, which may result in new or enhanced groundwater quality issues. The principal aim is to build a framework for developing a predictive tool for guidance in field spill events associated with these blended fuels. The phase partitioning and plume transport characteristics of alcohol and hydrocarbons in the fuel mixtures were studied via 2-D visualization experiments and quantitative pore water analyses. NAPL source generation and distribution characteristics were observed and compared for spills of various alcohol blended fuels to a model aquifer. As alcohol content in the fuel mixture increased, a higher fraction of the NAPL in the fuel was mobilized due to both cosolvency and phase mobilization. Variations in the size, shape, and saturation of the residual NAPL source generated from different alcohol fuel blends impacted the dissolution rates of the hydrocarbon contaminants and the longevity of the NAPL source. Ethanol was the alcohol studied in this research. A multi-component, multi-phase flow simulator, UTCHEM, was used to quantitatively evaluate the impact of key physical-chemical properties that influence the transport behavior of alcohol as well as the distribution of the hydrocarbon contaminants in porous media. Numerical simulations compared well with physical model experiments for ethanol blended fuels to the aquifer in water-saturated conditions.