When there’s contamination in soil or groundwater on adjoining or underlying property with chemicals of concern (COC) that can volatize, then there’s a potential risk of vapors (or soil gas) to migrate and reach indoor air space of residences, buildings and other structures.  Vapor intrusion assessment (or vapor encroachment screening) is an evaluation process that’s used to determine if there’s a potential for COC vapors to encroach upon a target property.  A property that’s being consider for purchase or redeveloped could be considered a target property.

 

Entrance of COC vapor into indoor air space presents a pathway for exposure that can be harmful to human health under certain circumstances.  When exposure to vapors occurs to occupants, then vapor intrusion into indoor air has taken place.  Humans can be exposed to COC by ingestion and dermal contact of contaminated soil or groundwater.  Human exposure to COC vapors by inhalation can occur when there’s vapor intrusion (VI).

 

Volatile COCs include volatile organic compounds (VOCs) such as chlorinated solvents and de-greasers (including tetrachloroethylene (PCE), trichloroethylene (TCE), 1,1Dichloroethane, 1,1-dichloroethylene (1,1-DCE), 1,2-dichloroethane (1,2-DCA), vinyl chloride, others).  Other volatile COC include semi-volatile organic compounds (SVOCs), petroleum hydrocarbons, and volatile inorganic compounds (ie. mercury). The common VOCs found in gasoline include benzene, toluene, ethylbenzene, and xylene (BTEX).

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Some areas we can help you are:

 

Field investigations, vapor intrusion (VI) management and mitigation

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Vapor Encroachment Screening (VES) – The VES is used to assess the potential for a volatile COC to migrate onto a target property.   If the VES determines that there is indeed the ‘presence or the likely presence’ of COC vapors, then a vapor encroachment condition exists.  A Vapor Encroachment Condition (VEC) is the presence or likely presence of COC vapor in the soil vadose zone of the target property. The VES processes uses ASTM E2600 Vapor Encroachment Screen on Property Involved in Real Estate Transactions or an equivalent acceptable standard practice. 

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Indoor air, and soil gas investigation and monitoring for COCs, utilize conventional and continuous real-time indoor air monitoring technology to measure contaminants and to map extent of contamination.

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Installation of vapor barrier, sub-slab depressurization and venting systems, implement other site specific vapor management and mitigation options.