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Abs: <\/strong>ITRC\u2019s 2007 guidance document, Vapor Intrusion Pathway:<\/em> A Practical Guideline, <\/em>primarily focused on chlorinated vapor intrusion (CVI). However, the focus of PVI document is petroleum vapor intrusion (PVI), a subset of vapor intrusion. Vapors from petroleum hydrocarbons rapidly biodegrade as they migrate through unsaturated, vadose-zone soils, greatly limiting the potential for the PVI pathway to be complete.<\/p>\n \u00a0<\/strong>ITRC\u2019s 2007 guidance document, Vapor Intrusion Pathway:<\/em> A Practical Guideline, <\/em>primarily focused on chlorinated vapor intrusion (CVI). However, the focus of this guidance document is petroleum vapor intrusion (PVI), a subset of vapor intrusion.<\/p>\n Vapors from petroleum hydrocarbons rapidly biodegrade as they migrate through unsaturated, vadose-zone soils, greatly limiting the potential for the PVI pathway to be complete. The biodegradation of petroleum hydrocarbon vapors is rapid comparing to slower anaerobic degradation of chlorinated compound vapors.<\/p>\n Biodegradation of petroleum hydrocarbons by indigenous microorganisms is characteristic of nearly all unsaturated soils. The potential for biodegradation of petroleum hydrocarbon vapors can be used to evaluate whether a site contaminated with petroleum compounds requires additional investigation of the vapor intrusion pathway.<\/p>\n The fundamental principle of this screening method is the \u201cvertical screening distance\u201d. The document provides an eight-step process for screening, investigating, and managing sites contaminated with petroleum hydrocarbons to address the PVI pathway.<\/p>\n The extent and rate to which this natural biodegradation process occurs is strongly influenced by the concentration of the vapor source, the distance the vapors must travel through soil from the source to potential receptors, and the presence of oxygen (O2<\/sub>) in the subsurface environment between the source and potential receptors.<\/p>\n The screening method is applicable for different types of petroleum sites with variability depending on whether the site is a smaller site or a larger petroleum industrial site.<\/p>\n Figure 1: PVI conceptual outcomes<\/strong><\/p>\n![\"\"](\"https:\/\/us.envguide.com\/wp-content\/uploads\/\/2018\/07\/\u56fe2.png\")
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