Analysis of Petroleum Site Vapor Intrusion Data

API is currently analyzing available soil gas and groundwater datasets to determine if there are reliable and easy to measure site characteristics that indicate conditions both favorable and unfavorable to bioattenuation.

Biodegradation is a widely recognized process for contributing to the attenuation of petroleum hydrocarbon vapors in the vadose zone. Yet cases where vapors do not significantly attenuate have been documented. Regulators and industry are equally motivated to understand the site-specific conditions that significantly increase or decrease the potential for a vapor intrusion.

Processes and conditions affecting oxygen demand and oxygen availability are thought to significantly affect bioattenuation in the vadose zone. The approach in this project involves analyzing field data to try to identify which combinations of site characteristics (e.g., source strength, distance from source to building, foundation area and type and possible other factors, e.g., organic carbon fraction) typically result in conditions of greater oxygen supply than demand (and thus, observed bioattenuation). It is hoped that this analysis will allow refinement of screening models that incorporate biodegradation and ultimately yield defensible, easy to use screening criteria.

API is collaborating with the regulators from the states of Utah and Colorado to interpret soil gas sampling results from petroleum sites. State regulators interested in joining this project should contact Harley Hopkins.

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File Size: 975 KB 
Version Date: January 19, 2007 
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Status Report – September 2006


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File Size: 1.2 MB
Version Date: September 2006
OS: PC/Mac
License: Free