Analysis of flow processes during TCE infiltration in heterogeneous soils at the Savannah River Site, Aiken, South Carolina

摘要

Contamination of soils and groundwater from volatile organic compounds (VOCs), such as organic solvents and hydrocarbon fuels, is a problem at many industrial facilities. Key to successfully characterizing, containing, and eventually remediating the contamination is a thorough understanding, based on sound scientific principles, of the complex interplay of physical, chemical, and biological processes in geologic media, which affect the migration and distribution of the contaminants, and their response to remediation operations. This report focusses on physical mechanisms that affect contaminant behavior under the conditions encountered at the Savannah River site (SRS). Although other contaminants are present at the site, for the purpose of this discussion we will restrict ourselves to the processes following a spill and infiltration of trichloroethylene (TCE), which is the main contaminant at the location of the Integrated Demonstration Project. We begin by briefly describing the main physical processes following release of TCE into the subsurface. Subsequently we will present simple engineering models that can help to evaluate contaminant migration processes in a semi-quantitative way. Finally, we will discuss results of detailed numerical simulations of TCE infiltration into a heterogeneous medium consisting of sands and clays. These simulations attempt to shed light on the initial distribution of contaminants at the site prior to the start of remediation operations. We also point out limitations of present numerical modeling capabilities, and identify issues that require further research in order that a realistic description of contaminant behavior in the subsurface may be achieved.