Constraints on mass balance of soil moisture during in situ vitrification

In situ vitrification (ISV) is an environmental remediation technology used to melt contaminated soil sites into more stable configurations. The behavior of water and other volatile constituents in the soil-melt system is important to the overall performance of the ISV technology. Mass and volume balance constraints are used to derive a method to indirectly estimate the volume of: (1) soil that dehydrates and releases water vapor to the off-gas, and (2) outside air pulled into the off-gas treatment system. These constraints allow us to speculate on whether some water may remain in the soil rather than being completely transported into the off-gas system. The method is tested with data from a field-scale test. Results suggest that, contrary to previous conceptual models, not all water that is vaporized reaches the surface and captured by the off-gas treatment system. It is probable that some percentage remains within the soil beneath and around the molten ISV mass.