Vapor in a Phase I

Contamination may be moving as vapor through the subsurface, on the subject property or toward it. The standard counts that as migration and does not require the separate vapor guide. Whether vapor becomes part of a finding depends on four things: whether a release is the source, whether its vapor is present or likely present at the subject property, whether the concern is a release or only indoor air quality, and whether an earlier closure looked at the pathway.

What the answer turns on

A release as the source. The recognized environmental condition (REC) definition asks about hazardous substances or petroleum products at the subject property owing to a release or a likely release (E1527-21, 3.2.73). Migration is their movement in any form, and the standard's examples of form include vapor in the subsurface (E1527-21, 3.2.53). Vapor is a way a release travels. The standard defines no vapor condition of its own.
Present or likely present at the subject property. When the site visit points to a likely release on a nearby property that could reach the subject property, the standard requires the geology, groundwater, topography and other environmental information to be evaluated for whether a REC at the subject property likely results (E1527-21, 9.4.6). The standard says subsurface vapor migration is described in a separate ASTM guide, and that nothing in the practice requires applying that guide (E1527-21, 3.2.53.1). It gives no vapor distance or screening step of its own.
A release, or only indoor air quality. Indoor air quality that has nothing to do with a release into the environment is a non-scope consideration (E1527-21, 13.1.5.7). The standard's appendixes are nonmandatory. The one on non-scope issues says the federal agency regulates indoor air quality, in general, only where the impact comes from releases to subsurface soil or groundwater, which it calls vapor intrusion (E1527-21, X6.8). The legal background appendix, citing that agency's guidance, says vapors which entered a building from a release outside it can bring liability under the federal cleanup law (E1527-21, X1.1.1.2).
Whether an earlier closure looked at the pathway. A past release can lose its standing as a historical REC or a controlled REC if a migration pathway not previously known or evaluated is identified (E1527-21, 3.2.17.1, 3.2.39.1). For a closed case, establish which pathways the closure evaluated. An activity and use limitation should say which exposure pathway and medium it controls, and its definition names soil vapor among the media (E1527-21, 3.2.2, 5.3).

The records that bear on it

Government records and the file. The standard sets one required minimum distance for each kind of list, whatever the form of migration (search distances). The environmental professional may reduce a distance with stated reasons, weighing how far substances are likely to migrate in the local geology and hydrogeology (E1527-21, 8.1.2.1). For a listed subject property or adjoining property the file should be reviewed, or the report explains why a review is not warranted (E1527-21, 8.2.3.1). In the file, look for which media and pathways were evaluated.
Controls. Registries of institutional and engineering controls are searched for the subject property (state, federal). Both pages name vapor mitigation among engineering controls.
Site visit and interviews. Odors that are strong, pungent or noxious, and where they come from, are among what the site visit looks for (E1527-21, 9.4.13). It need not identify conditions under floors or behind walls, and the practice includes no sampling (E1527-21, 7.4, 9.2.4.2). The owner, key site manager and user are asked for site investigation reports and risk assessments (E1527-21, 10.8.1).

What the federal rule says

The rule never mentions vapor. What its inquiry is meant to find:

conditions indicative of releases and threatened releases of hazardous substances on, at, in, or to the subject property

40 CFR 312.20(e)

Among the factors the professional may weigh in changing a search distance:

Potential migration pathways (e.g., groundwater flow direction, prevalent wind direction)

40 CFR 312.26(d)(6)

How it is written up

The standard has no separate class or report section for vapor; it is one of the ways substances from a release may be present or likely present at the subject property (E1527-21, 3.2.53). The opinion gives the reasons why a finding does or does not fall in each class it pertains to (E1527-21, 12.5, 12.6).

Where the professional concludes vapor from a release is present or likely present at the subject property, the opinion names the release and why its vapor has likely arrived. Unless judged a de minimis condition or a historical REC, the REC is listed in the Conclusions, and the professional should give an opinion on additional investigation (E1527-21, 3.2.20, 3.2.39, 12.7, 12.8).

Where the professional concludes otherwise, the opinion gives its reasoning on the same facts (E1527-21, 12.6).

Where the concern is indoor air quality unrelated to a release, it is outside the practice, and can be taken up as an additional service agreed between the user and the professional before the work starts (E1527-21, 1.4, 13.1.5.7).

Observation of part of the subject property on the site visit may be what cannot be had. Required information that good faith efforts could not obtain is a data gap, significant if it affects the ability to identify a REC: named in the Findings with the sources consulted, discussed in the Opinions and listed in the Conclusions (E1527-21, 3.2.19, 3.2.78, 12.5.1, 12.6.2, 12.7).

This page is general reference for environmental professionals. It does not classify any property. ASTM E1527-21 is the standard and is not reproduced here; the judgment of the environmental professional on the facts governs.