Petroleum vapors from leaking underground storage tanks have the potential to enter buildings, where they might pose a risk to the health of occupants. This problem is called petroleum vapor intrusion (PVI). Field research has found that the potential for PVI is limited by biodegradation and depends on site-specific factors, including:
- location and strength of the petroleum source of the vapors,
- depth of contamination, and
- characteristics of the building.
Models offer good ways to integrate and better understand the dynamics of PVI, but their use has been hampered by limited site-specific data. EPA’s PVIScreen addresses this limitation by treating the model results as one line of evidence for PVI and by incorporating an uncertainty analysis within the model. It is compatible with EPA guidance for assessing PVI at leaking underground storage tank sites.
PVIScreen automatically conducts an uncertainty analysis, which repeatedly runs the model with differing values of site-specific factors. Some of these factors may be uncertain, while others are known. For example, the ceiling height of the building is likely to be known. The exact depth of the petroleum source, in contrast, might be unknown and could be treated as within a range of values. Typically, the model is run 1000 times using these various factors and input quantities.
Through this process, the model makes uncertainty analysis practical, as running the model individually for all the possibilities would be cumbersome. The model’s documentation provides descriptions of the basis of the approach, along with required inputs, example problems, and the theoretical background of the model.
PVIScreen extends the concepts of a prior model (BioVapor), which accounted for oxygen-driven biodegradation of multiple constituents of petroleum in the soil above the water table. It was tested against the BioVapor code and applied to case examples in Utah and Oklahoma. Model simulations are in agreement with EPA’s Petroleum Vapor Intrusion Database, which contains field data that illustrate and document the attenuation of concentrations of petroleum compounds in soil gas with distance above the source of the vapors.
- Copy the PVIScreen distribution file (PVIScreen.zip) to C:\MyDocuments\PVIScreen and extract all files to this location.
- To open, double click on the PVIScreen.jar file. All needed data files and examples will be available in the SRC\systemData and projects\examples directories. Note: If the model fails to execute, make sure that the Java runtime environment is in the computer’s path. Check with your system administrator for guidance.
An Approach for Developing Site-Specific Lateral and Vertical Inclusion Zones within which Structures Should be Evaluated for Petroleum Vapor Intrusion due to Releases of Motor Fuel from Underground Storage Tanks
- Video from PVIScreen Webinar Presentation (3/14/18) - Assessing Variability in Petroleum Vapor Intrusion with PVIScreen
Send e-mail to: Aaron Ferster (firstname.lastname@example.org)