Fill of unknown origin

Records or the site visit show the subject property was filled, and nobody can say where the fill came from. The standard names fill of unknown origin as something to look for and does not say what class it makes. Whether there is a recognized environmental condition (REC) depends on four things: whether the ground is fill, what the fill is made of, when and by whom it was placed, and what evidence there is of hazardous substances or petroleum products in it.

What the answer turns on

Whether the ground is fill. Fill dirt is defined as earth brought from off site to fill holes or depressions, build mounds or otherwise change the grade artificially; small amounts used in normal landscaping are left out (E1527-21, 3.2.33). The site visit item for solid waste covers ground that looks artificially graded, ground filled with fill of unknown origin, and mounds or depressions, each where it points to buried trash, construction or demolition debris or other solid waste (E1527-21, 9.4.25).
What the fill is made of. A REC needs hazardous substances or petroleum products (E1527-21, 3.2.73), and the standard does not say that earth or debris is either. Its appendixes are nonmandatory. The one on non-scope issues notes that asbestos-containing materials are excluded from the federal statute while part of a standing building, and may lose that exclusion once the building is demolished and they are buried in soil (E1527-21, X6, introduction). Establish whether the fill is earth, debris, trash or other waste.
When and by whom it was placed. Placing fill dirt is a developed use, and the history of uses runs back to the first developed use or to 1940, whichever is earlier (E1527-21, 8.3.8). The environmental professional considers what releases past uses could have led to (E1527-21, 8.3.1). For a likely release, the appendix on the REC definition points to what a feature or operation involved, how long it lasted and when (E1527-21, X4.1). A footnote in the legal background appendix cites court decisions that treated using contaminated soil as fill, and spreading it by grading, as new disposals (E1527-21, X1.3.1.2, footnote 157). Establish the years of filling, who did it and any record of the source.
Evidence in the fill. Odors, drums and containers, stained soil and stressed vegetation are site visit features (E1527-21, 9.4.13, 9.4.15, 9.4.23, 9.4.24). The practice includes no sampling (E1527-21, 7.4). Without earlier data, the opinion turns on whether presence is likely: not proved, but what a reasonable observer would expect on the professional's logic, experience and stated evidence (E1527-21, 3.2.73.1).

The records that bear on it

Historical sources. Aerial photographs and historical topographic maps are reviewed when the professional judges them applicable, likely to be useful and reasonably ascertainable (E1527-21, 8.3.8). Compare dates for a pond, pit or low area that disappears, or a grade that changes.
Government records. Landfill and solid waste disposal site lists are a standard source, with a required minimum search of half a mile (landfills and solid waste; E1527-21, 8.2.2, Table 2). Texas publishes an inventory of closed landfills that takes in unauthorized landfills and illegal dumps, as it stood in the late 1990s (Texas). Ohio posts an archived list of about 1,200 abandoned dumps or landfills that it no longer maintains (Ohio), and has rules for work on or near land once used for waste disposal (Ohio).
Site visit. The solid waste item is described in the report, found or not (E1527-21, 9.4, 9.4.25). A road or path with no apparent outlet has its use identified, to judge whether it was likely an avenue for disposal (E1527-21, 9.2.2).
Documents. Before the site visit the owner, key site manager and user are asked for geotechnical studies, site investigation reports and solid waste disposal permits (E1527-21, 10.8.1).

What the federal rule says

The rule does not mention fill. Among what the inquiry must seek to identify:

Waste management and disposal activities that could have caused releases or threatened releases of hazardous substances;

40 CFR 312.20(e)(1)(iii)

On data gaps the rule adds:

Sampling and analysis may be conducted to develop information to address data gaps.

40 CFR 312.20(g)

How it is written up

The filling is described with the other identified uses (E1527-21, 8.3.8). Fill is a finding when the professional judges it may indicate hazardous substances or petroleum products present or likely present at the subject property (E1527-21, 12.5).

Where the professional concludes they are present or likely present in the fill because of a release or likely release, the opinion gives the grounds: what the fill holds, when and by whom it was placed, and any data. 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, 12.6, 12.7, 12.8).

Where the professional concludes otherwise, the opinion on a finding gives its reasoning on the same four facts (E1527-21, 12.6). A risk to the user's planned use that lies outside the REC definition can be discussed as a business environmental risk where the terms of engagement call for it (E1527-21, 3.2.11, 12.10).

Aerial photograph or topographic map coverage of the years of filling 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.