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One Environmental Professional’s Take on ASTM’s Revised Vapor Encroachment Screening Standard

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March 9, 2016 6 mins

In December 2015, ASTM Subcommittee E50.02 (Real Estate Assessment and Management) approved revisions to the Standard Guide E2600 for Vapor Encroachment Screening on Property Involved in Real Estate Transactions. The new E2600-15 Standard Guide is an update to E2600-10, which was published in 2010 as an update to the original guide published in 2008 (E2600-08).

The purpose of E2600 is to provide practical guidance and a useful process for conducting a vapor encroachment screen (VES) on a property parcel involved in a real estate transaction with respect to chemicals of concern (COC) that may migrate as vapors into the vadose zone of a property as a result of contaminated soil and/or groundwater on or near the property. Jim Bartlett, Senior VP at EMG and Vice Chairman of ASTM Subcommittee E50.02, recently authored a white paper titled “Overview of Recent Revisions to ASTM E2600 Standard Guide for Vapor Encroachment Screening on Property Involved in Real Estate Transactions.” Jim graciously offered to answer a few questions about the revisions for LightBox EDR® Insight.

In a nutshell, what were the types of changes ASTM made to the updated guide?
Jim Bartlett: The workgroup made four main types of revisions to the E2600-15 Standard Guide including changes to terminology, improved scientific content, simplified guidance for making conclusions, and updated references to additional sources of information.

What do you view as the most significant change to the E 2600 Guide under the December revisions?
JB: EPs and Users now have vastly simplified guidance for making conclusions related to Vapor Encroachment Conditions (VEC). A VEC now either “exists” or “does not exist”. The goal of the previous guide was to define a procedure for identifying whether a VEC “exists, likely exists, cannot be ruled out, or can be ruled out because a VEC does not or is not likely to exist.” Many EPs and users found these multiple scenarios too difficult to apply, which led the Task Group to simplify this key concept. The industry likes to see clear results in a report, and I think this one change alone could result in greater adoption of the standard.

Can you give readers a general sense of the types of conditions that would lead to the conclusion that ‘a VEC exists?’
JB: A ‘VEC exists’ determination may be appropriate when there are known Chemicals of Concern (COC) contaminating soil and/or groundwater on or near the target property. The guide gives EPs a process for evaluating the areas of concern and corresponding vapor encroachment potential of each COC, which can be adjusted based on site-specific conditions such as soil type, natural or man-made preferential pathways, topography, and groundwater data, etc. The concept of “adjusted AOCs” is new to the guide, and makes the screening and VEC determination process more practical and reasonable than the previous version.

Explain how and why ASTM clarified the migration of chemicals of concern into the vadose zone of the target property.
JB: This was another notable terminology improvement. The Guide previously addressed vapor migration “onto” a property or “to the subsurface”, but now clarifies that the migration of COCs “into the vadose zone” of the target property is the more accurate concern. The soil pore space and space between soil particles and capillary fringe that comprise the vadose zone typically contains air or other gases, and can provide a migration pathway for volatile and semi-volatile COCs. The Guide defines the vadose zone as “the zone between the land surface and the water table within which moisture content is less than saturation (except in the capillary fringe) and pressure is less than atmospheric.” Though the term was present in previous versions, its importance in conveying the concept of vapor migration has increased since the 2013 revision to the E1527-13 Phase I ESA Standard Practice, which requires the consideration of contaminant vapor migration pathways in addition to soil and groundwater pathways.

How does the vapor encroachment screening process relate to the Phase I ESA process outlined in ASTM E 1527-13?
JB: The general VES process is a two-tiered screening that takes information from a Phase I ESA investigation or similar type of investigation to determine if a VEC exists at the target property (referred to as Tier 1) and conduct additional screening to obtain greater certainty where desired (Tier 2). As with the previous version of the Guide, it emphasizes that a Tier 1 screening may be conducted in conjunction with a Phase I ESA or similar investigation or may be performed as a standalone service (but not as a replacement for a Phase I ESA). For environmental professionals and users of Phase 1 Environmental Site Assessments, it is important to be reminded that performance of a VES in accordance with E2600 is not a requirement of ASTM E1527-13, and does not alter or in any way define that practice. Similarly, E2600 does not constitute, expand or in any way define “All Appropriate Inquiry” as defined by the EPA. The primary benefit the guide gives to EPs and users is a practical roadmap for addressing the potential migration of contaminants in the vadose zone which could ultimately impact commercial real estate transactions and/or pose vapor intrusion risks to building occupants.

What are some of the other changes EPs will see in the revised E 2600?
JB: EPs and Users should take note of the revised terminology section, where the workgroup made material changes to 10 defined terms within the guide. No new terms were added, but one previously-used acronym (AOC – area of concern) was added correctively. There are also six expanded “Discussion” sections which convey additional scientific detail and clarifications of key concepts like “preferential pathways” and “recognized environmental conditions.”

What are some of the key changes to the Legal Background appendix?
JB: There were several updates to the Legal Background appendix related to the USEPA’s revised guidance on vapor migration that occurred in 2013 with the final AAI Rule incorporating E 1527-13, and other relevant Federal references. The appendix also added Section X1.6 which describes the relationship between Vapor Encroachment (VE) and Vapor Intrusion (VI), where VE is “the potential for migration of vapor contaminants onto (or through the subsurface of) the target property”, while VI, a separate and distinct concept, “evaluates potential exposure risks to persons within a building resulting from vapor migration into structures.” Section X1.6.2 clarifies that Vapor Intrusion is beyond the scope of the guide. Since it is VI, and not VE, that often drives regulatory actions at properties under CERCLA and other laws; the guide makes special reference to Appendix X5, which includes updated references to state and federal vapor intrusion regulatory programs.

What advice would you give to someone who isn’t yet up to speed on vapor encroachment or the E 2600 standard?
JB: I’d start by obtaining a copy of the new Standard Guide from ASTM. It contains a wealth of useful technical sources; specifically, the updated resources section is a very practical toolbox for any parties researching or contending with vapor encroachment risks. The standard also contains nine appendixes which provide legal background; EP qualifications; sample questionnaire; recommended contents; regulatory resources; COC tables; vapor intrusion (VI) assessment guidance and mitigation alternatives; and supplemental bibliography.

• Get a full copy of the Standard Guide for Vapor Encroachment Screening on Property Involved in Real Estate Transactions from
• For a copy of EMG’s white paper titled Overview of Recent Revisions to Standard Guide for Vapor Encroachment Screening on Property Involved in Real Estate Transactions visit:
• Questions or comments related to this summary may be directed to Jim Bartlett

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