Estimation of Contaminant Subslab Concentration in Vapor Intrusion Including Lateral Source-Building Separation.

Area of Science:

• Environmental Science
• Geology
• Chemical Engineering

Background:

• Current vapor intrusion models often assume homogenous subsurface contaminant sources.
• Groundwater data from monitoring wells are typically used to represent source concentrations for multiple buildings.
• Lateral source-building separation can significantly influence vapor intrusion assessments.

Purpose of the Study:

• To develop a novel method for estimating subslab contaminant concentrations that incorporates lateral source-building separation.
• To provide an explanation for the observed variability in vapor intrusion attenuation factors.

Main Methods:

• Utilized a conformal transform technique to develop the new estimation method.
• Compared the results of the new method with a three-dimensional numerical model.
• Analyzed data from the EPA vapor intrusion database.

Main Results:

• The new method successfully estimates subslab contaminant concentrations considering source offset.
• The developed method offers a potential explanation for the wide range of attenuation factors in the EPA database.
• Results align well with those from a 3D numerical model.

Conclusions:

• The developed conformal transform method provides a more realistic approach to vapor intrusion modeling.
• Accounting for lateral source-building separation is crucial for accurate vapor intrusion assessments.
• This research contributes to a better understanding of contaminant transport and exposure pathways.