Laboratory Characterization of Contaminant Transfer during Boiling

Chlorinated volatile organic compounds (CVOCs) in fractured, low permeability media can be a long-term source of groundwater contamination, and they are among the most challenging sites for remediation. The objective of this research is to characterize contaminant mass transfer in low permeability clays at boiling temperatures. The research is motivated by the need to advance understanding of the thermal remediation of tight sediments containing CVOCs. The experimental design considers a cylinder normal to the plane of a fracture. 1,2-dichloroethane (DCA) was dissolved in degassed water containing non-volatile bromide and this solution was mixed with dry kaolin powder to create the clay used in the tests. The observations indicate that the permeability of the clay significantly increased by heating as a result of fracture growth that occurs during heating and water boiling. This research confirms the ability of thermal remediation to remove volatile contaminants from the matrix in fractured clays. The recognition of a new mechanism for recovery by vapor-driven fractures suggests that remediation of low permeability may be more feasible than previously recognized.