Use of Mass-Flux Measurement and Vapor-Phase Tomography to Quantify Vadose-Zone Source Strength and Distribution

Use of advanced technologies could improve evaluation of vadose zone source impacts on groundwater and vapor intrusion, leading to improved remediation decisions.

Environmental Security Technology Certification Program, Alexandria, Virginia

The goal of this project was to demonstrate that the multistage vapor-phase contaminant mass discharge (MS-CMD) test and vapor-phase tomography (VPT) can effectively characterize persistent volatile organic compound (VOC) sources in the vadose zone and measure their associated mass discharge. It is anticipated that these technologies will improve evaluation of vadose zone source impacts on groundwater and vapor intrusion.

The U.S. Department of Defense (DoD) has focused significant effort on characterizing and treating chlorinated solvent sources in groundwater. There are two primary concerns associated with sites that contain vadose zone volatile organic compound (VOC) sources. First, discharge of contaminant vapor from the vadose zone source may impact the underlying groundwater. Second, contaminant vapor from the vadose zone source may migrate to the land surface and transfer into buildings, thereby causing vapor intrusion. The DoD manages thousands of sites wherein the vadose zone is contaminated by chlorinated solvents and other VOCs.