A limited Phase II, or limited subsurface investigation

ASTM E1903-19 uses neither term. The word limited appears in it only in other senses, such as the title of the transaction screen practice, E1528, and the note that a person's standing as a Phase II Assessor can be confined to one type of assessment (E1903-19, 1.1.2, 3.1.32). The phrase subsurface investigation is not in E1903-19 either. The Phase I standard's nonmandatory legal appendix uses it: a user whose Phase I identifies RECs may want additional subsurface investigation, which that appendix says is commonly called a Phase II (E1527-21, X1.6.3).

What E1903-19 has instead is a scope set by the user's objectives, and requirements to document that scope and the constraints on the work (E1903-19, 1.1, 1.3, 5.1). The standard defines a Phase II ESA as an assessment done by its process (E1903-19, 3.1.33), and the report carries a statement of conformance where all of the standard's elements are followed (E1903-19, 9.2.1). For a narrow assessment, then, what matters is whether it follows that process, not its label.

The degree of assessment

As many rounds as the objectives need. The practice requires only as many rounds of planning, carrying out and evaluating as the Statement of Objectives calls for (E1903-19, 6.3).
Every step, scaled. The general steps must be taken in every Phase II, in the manner and detail the objectives call for: the question, the areas, the conceptual model, the sampling plan, the sampling, validating the model, the conclusions and the report (E1903-19, 6.4).
General answers need less. Objectives that need only general conclusions may call for less testing and fewer rounds; detailed conclusions held with high confidence may call for more (E1903-19, 1.4.1).
Not exhaustive. A Phase II does not generally require an exhaustive assessment (E1903-19, 4.2.2). Once the information lets the Phase II Assessor conclude, by the scientific method, that the question has been answered, no further assessment is needed to meet the objectives (E1903-19, 4.1.2.3).
The floor. At a minimum, the sampling plan must allow the media to be collected from every area where target analytes are, or are likely to be, at their highest concentrations (E1903-19, 7.5.1). It may go further when the question needs the distribution of target analytes or their change over time, not only whether they are there (E1903-19, 7.5.2).

Full characterization is not required

Full site characterization is not required in every case under the practice, though the practice can be used to carry one out if the user's objectives call for it (E1903-19, 1.3.3). Site characterization evaluates target analyte presence throughout a site affected or potentially affected by releases. It typically also examines the site's geology, water conditions and engineered features that influence that presence, along with receptors and exposure mechanisms (E1903-19, 3.1.46). Finding target analytes present does not mean their full extent is known (E1903-19, 3.1.35).

One round may not be enough

One round of sampling and testing may leave the data short of the chosen objectives; if so, the practice contemplates further rounds until the data suffice, though the user may instead redefine the objectives to fit the data at hand, or end the investigation without meeting them (E1903-19, 1.3.2). Either way, the report must say in what respect the data fall short (E1903-19, 1.3.2). Any further round should start with both sides reweighing the question and the cost and likely effectiveness of more work (E1903-19, 7.7.1.2).

Writing down the limits

In the Statement of Objectives. It must identify and describe limits of schedule, cost or budget, including any limit fixed in advance on the scope or on the number of sampling rounds; if the limits will keep the Phase II from meeting the practice, the statement must either adapt the objectives to fit them or describe their expected effect (E1903-19, 5.1.2).
In the field. Carrying out the sampling includes taking note of any physical or logistical obstacle to the plan, such as a barrier at a planned location or too little sample recovered (E1903-19, 6.4.5). The record must identify departures from planned sampling. If a departure affects achievement of the objectives, the assessor and user may reconsider or revise the plan or model (E1903-19, 7.6).
In the report. The report must explain the work and its rationale, identify departures from planned sampling, and discuss whether those departures substantially affect achievement of the objectives (E1903-19, 9.2). The standard's nonmandatory appendix on report formats suggests the introduction name what was left out that a reader might have expected, such as likely release areas not addressed, and say why (E1903-19, X3.2.4).

When only some areas are assessed

Where assessing only some of a property's releases and likely release areas can meet the objectives, a conclusion that no further inquiry is warranted covers only the ones assessed, and the report shall say so (E1903-19, 8.1.4). If the objectives permit it, further work on a likely release area may end when Phase II findings provide no reasonable grounds to believe analytes occur there at concentrations of concern. The standard gives an assessment not aimed at establishing CERCLA landowner liability protection as an example (E1903-19, 8.1.4). The Phase II Assessor must still designate every area that has to be investigated to meet the objectives (E1903-19, 7.3.4).

When the objectives are not met

Whenever a Phase II falls short of its written objectives, the results must be interpreted against those objectives and the shortfall explained and evaluated (E1903-19, 8.1.5). Unless the user redefines the objectives to fit the data at hand, the Phase II Assessor should decide whether more Phase II work is needed and what it should cover (E1903-19, 8.1.5). The conclusions must answer the questions the Phase II set out to address, or state clearly why they cannot be answered and what conclusions can be drawn, if any (E1903-19, 6.4.7).

This page is general reference for environmental professionals. It does not assess any property. ASTM E1903-19 is the standard and is not reproduced here; the judgment of the Phase II Assessor on the facts governs.