Soil Vapor Testing
The purpose of soil vapor testing is to evaluate whether volatile chemicals present in the subsurface could impact indoor air quality through vapor intrusion into existing or future buildings. Soil vapor investigations are commonly performed alongside soil and groundwater testing to help characterize the nature, extent, and movement of subsurface contamination.
The history and operational use of a site typically guide the selection of analytical parameters and compounds of concern. Vapor intrusion investigations may include petroleum hydrocarbons, chlorinated solvents, fuel oxygenates, fixed gases, methane, hydrogen sulfide, and other volatile organic compounds (VOCs) depending on site conditions and regulatory requirements.
Examples
- When USTs or fuel pipelines are / were present, fuel oxygenates (MTBE, ETBE, DIPE, TAME, TBA) should be included for analysis.
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Sites involving underground storage tanks (USTs) or fuel pipelines may require analysis for fuel oxygenates including MTBE, ETBE, DIPE, TAME, and TBA.
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Oilfield sites and hydrocarbon-impacted properties may require evaluation of fixed and biogenic gases such as oxygen (O2), carbon dioxide (CO2), and methane (CH4).
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Petroleum sites, dairies, wetlands, landfills, septic zones, intertidal areas, coal-containing soils, and fill areas may require methane and hydrogen sulfide evaluation due to potential vapor accumulation concerns.
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Sites impacted by chlorinated solvents stabilized with 1,4-dioxane may require specialized low-level analysis for 1,4-dioxane and associated chlorinated breakdown compounds.
Vapor intrusion investigations are performed when volatile chemicals present in soil vapor or groundwater could migrate into nearby buildings and affect indoor air quality. Soil gas samples are collected to evaluate the lateral and vertical extent of contamination and to support environmental risk assessment and remediation planning.
Sampling programs often begin in open areas and may progress toward existing or proposed structures if contaminant trends indicate potential vapor migration concerns. Sub-slab vapor, paved areas, and indoor air may also be evaluated where VOC accumulation beneath impermeable surfaces or structures is a concern.
Additional factors that may warrant indoor air or vapor intrusion investigation include chemical odors, reported physiological symptoms, wet basements, confined spaces, or the presence of potentially explosive vapors.