Soil Vapor Testing & Mitigation

Soil Vapor Testing & Intrusion Mitigation

Soil vapor testing is performed to evaluate vapor-phase contamination underground.  The overall purpose is to determine the risk of hazardous chemicals migrating into a building space.   The process typically includes drilling at multiple locations on a property, and strategically installing soil gas sampling devices underground.  Vapor samples are then collected and analyzed by a laboratory. Updated October 18, 2019.

Methane Soil Vapor Test

Methane is an odorless gas that is usually affiliated with petroleum fields and landfills.  Methane soil vapor can migrate underground, and accumulate inside buildings over time.  Methane soil vapor has become a growing concern in most areas of Southern California, such as Los Angeles and Orange County.

Methane Soil Gas Tests are designed to screen the soil under properties for combustible hydrocarbon content.  Based on the results of a methane soil test, a Methane Mitigation System can be designed to prevent its intrusion into buildings.

Methane Testing initially includes a shallow probe soil gas survey. Afterwards, a drilling rig is used to drill and install multiple sampling zones underground.

Methane Testing Shallow Soil Gas Probe – Photo Credit: University of Texas at Austin & Bureau of Economic Geology

Soil Vapor Testing for Other Chemicals

Depending on the historical land use of a property, a soil vapor test can be optimized to screen for volatile organic compounds (also known as VOCs). This covers a variety of commonly used industrial solvents and petroleum-based products.

A Phase 2 Environmental Investigation typically incorporates shallow soil vapor testing for VOCs and hydrocarbons.  Soil vapor data is used to determine whether contamination exists in the subsurface and whether a potential human health risk exists.

©John S. Quarterman

Human Health Risk Assessment

A Human Health Risk Assessment is a scientific assessment of the theoretical health risk to occupants or users of a property posed by underlying contamination.  Soil vapor testing data is used for the risk assessment calculation.  Guidelines for this assessment are from the American Society for Testing and Materials (ASTM), the California EPA, the U.S. EPA, and the Department of Toxic Substances Control (DTSC).  A Human Health Risk Assessment (also known as an HHRA) also provides a screening-level analysis of the potential indoor air quality from vapor intrusion.

 For more information about soil vapor testing, vapor intrusion mitigation and health risk assessment, call (888) 930-6604 to speak with a licensed professional engineer or geologist.

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