Environmental Site Assessments (ESAs) help to safeguard commercial/industrial real estate buyers against liability for cleaning up hazardous environmental contaminants. While these assessments, such as the Phase I ESA, tend to focus on the presence or likely presence of any hazardous substances or petroleum products in, on, or at a property, buyers should be aware of the risks of future vapor encroachment from nearby properties.

Left unchecked, encroachment could lead to vapor intrusion originating from sources in the vicinity of the property to be purchased. For this reason, buyers are encouraged to consider vapor encroachment screening when procuring pre-purchase environmental assessment services.  In fact, the current Phase I Standard (ASTM Standard Practice 1527-13-Environmental Site Assessments: Phase I Environmental Site Assessment Process) now references vapor encroachment screening as an appropriate means of evaluating contamination migration to the property via the subsurface.

What is Vapor Encroachment Screening?

Vapor encroachment screening evaluates the potential for future vapor intrusion onto a property, either from an on-site source or from subsurface contamination in the local vicinity.

The baseline standard for vapor encroachment screening is E 2600-10, published by the American Society for Testing and Materials in 2010. Under this standard, screening is conducted according to a two-tiered approach:

  • Tier 1 involves identifying sites in the vicinity of the subject site that can be potential sources of vapor.
  • Tier 2 seeks to identify if a vapor encroachment condition exists, can potentially exist, or can be ruled out.

Initially, Tier 2 comprises a review of regulatory files and records, in the hope that these will provide the location of contamination sources and associated contaminant plumes. If the review does not provide this information, the next step is to take samples of groundwater, soil or soil gas for analysis.

The Value of Vapor Encroachment Screening

Vapor intrusion within commercial premises can have potentially serious consequences for the site owner. Depending on the nature of the vapor, the threat to health of building occupants could result in costly business disruption or could hamper development plans. Vapor encroachment screening prior to purchase therefore, is not only prudent, but necessary to avoid expensive surprises further down the line.

ATC specializes in ESAs and provides vapor encroachment screening services in accordance with ASTM E2600-10. To find out how we can help you with your commercial property purchase, construction or development plans, please contact us.