An Evaluation of Vapor Intrusion Into Buildings through a Study of Field Data

A systematic examination of cases on file with the Massachusetts Department of Environmental Protection was undertaken to identify a universe of sites with volatile organic compound (VOC) contamination in groundwater in close proximity to buildings. Such locations were grouped according to site variables, such as contaminants of concern and concentrations in various media; soil type; depth to groundwater; distance to building; and building construction. Indoor air, soil gas, and/or groundwater field data collected from these sites was then assembled and used to: (1) evaluate available transport models which describe the intrusion of vapors into buildings and predict indoor air contaminant concentrations resulting from the volatilization of VOC s in the subsurface; (2) examine the validity of established regulatory criteria; (3) identify specific trends and field conditions which appear to most influence vapor phase contaminant migration and intrusion processes; and (4) evaluate the possibility of vapor migration being inhibited by a "freshwater lens".