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Parameter Sets for Upper and Lower Bounds on SOIL-TO-INDOOR-AIR CONTAMINANT ATTENUATION PREDICTED BY THE JOHNSON AND ETTINGER VAPOR INTRUSION MODEL
Citation:
TILLMAN, F. D. AND J. W. WEAVER. Parameter Sets for Upper and Lower Bounds on SOIL-TO-INDOOR-AIR CONTAMINANT ATTENUATION PREDICTED BY THE JOHNSON AND ETTINGER VAPOR INTRUSION MODEL. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 41(27):5797-5806, (2007).
Impact/Purpose:
To assist decision-making by improving approaches to subsurface contaminant transport modeling based on evaluation of field observations and subsequent development of appropriate modeling approaches and tools.
Description:
Migration of volatile chemicals from the subsurface into overlying buildings is known as vapor intrusion (VI). Under certain circumstances, people living in homes above contaminated soil or ground water may be exposed to harmful levels of these vapors. A popular VI screening-level algorithm widely used in the United States, Canada and the U.K. to assess this potential risk is the Johnson and Ettinger (J&E) model. Concern exists over using the J&E model for deciding whether or not further action is necessary at sites as many parameters are not routinely measured (or are un-measurable). Using EPA-recommended ranges of parameter values for nine soil-type/source depth combinations, input parameter sets were identified that correspond to best and worst case results of the J&E model. The results established the existence of generic best and worst case parameter sets for maximum and minimum exposure for all soil types and depths investigated. Using the generic worst case/best case parameter sets, an analysis can be performed that, given the limitations of the input ranges and the model, bounds the indoor air exposures in a vapor intrusion investigation.