Emergency generator with a fuel tank

The subject property has an emergency generator fed by its own fuel tank: above ground, in a basement or vault, or buried. The tank alone does not settle whether there is a recognized environmental condition (REC). That depends on four things: where the tank sits and whether the federal tank rule counts it as underground, whether there is evidence of a release, whether its condition poses a material threat of one, and what the tank's history shows.

What the answer turns on

A REC is hazardous substances or petroleum products present at the subject property because of a release, likely present owing to a release or a likely one, or present where conditions make a future release a material threat (E1527-21, 3.2.73). The federal tank rule, 40 CFR part 280, says which generator tanks it covers; it classifies nothing under the standard.

Where the tank sits, and whether the tank rule counts it. The standard's underground storage tank (UST) is a tank, with its connected underground piping, whose volume is 10 percent or more below the ground surface (E1527-21, 3.2.93). Part 280 uses the same share, leaves out a tank standing on or above the floor of a basement or other underground area (40 CFR 280.12), and excludes a system of 110 gallons or less (40 CFR 280.10(b)). It calls systems that store fuel only for emergency power generators previously deferred: one in the ground by October 13, 2015 had until October 13, 2018 to meet subpart D, and a later one meets all applicable requirements at installation; one at a licensed nuclear power plant is, on conditions, left out of subpart D (40 CFR 280.10(a)(1), (c)(4)). Subpart D has owners and operators provide a method of release detection that "Can detect a release from any portion of the tank and the connected underground piping that routinely contains product" (40 CFR 280.40(a)(1)), and a petroleum tank "must be monitored for releases at least every 30 days", with exceptions (40 CFR 280.41(a)). A system that cannot apply a complying method has to go through the rule's closure procedures, and for previously deferred systems that runs from the dates above (40 CFR 280.40(c)). A generator tank with less of its volume below ground is outside part 280's definition.
Evidence of a release. The standard's appendixes are nonmandatory. Appendix X4 gives stained soil under an aboveground petroleum tank as an observation that could be direct evidence of a release (E1527-21, X4.1). A release that is found is weighed against the de minimis definition (E1527-21, 3.2.20).
A material threat. Three things make one: the threat is obvious, a release is likely to follow, and the environmental professional judges that the release would likely affect public health or the environment (E1527-21, 3.2.52, 3.2.55). Appendix X4 illustrates with this equipment: an aboveground tank said to hold diesel for an emergency generator, outdoors on gravel with no roof, bollards or containment structure, damaged, with no staining beneath. Its result, a REC for the material threat, rests on the assessor's opinion of the tank's obvious condition; the appendix says its examples are not to be applied universally (E1527-21, X4.3).
The tank's history. The professional considers what releases past uses, past storage among them, could have led to (E1527-21, 8.3.1, 9.4.2). Establish how long the generator has stood there, whether an earlier tank fed it, and what became of that tank.

The records that bear on it

Tank registrations. Registered tank lists are a standard source, searched for the subject property and adjoining properties (registered storage tanks; E1527-21, 8.2.2, Table 2). Georgia says its tank program regulates emergency generators as well as UST systems. Texas names aboveground tanks of 1,100 gallons or less among its common exemptions and exclusions.
Release records. The required minimum search covers the subject property for federal release reports and half a mile for leaking tank lists (E1527-21, 8.2.2, Table 2).
Documents and interviews. The owner, key site manager and user are asked whether they know of tank registrations and spill prevention plans (E1527-21, 10.8, 10.8.1). For a buried tank under part 280, the results of release detection sampling, testing or monitoring are kept for at least one year, with exceptions (40 CFR 280.45(b)); ask for them.
Site visit. Tanks, vent pipes, fill pipes and access ways are looked for, and a tank's description should give its construction, contents, capacity and age (E1527-21, 9.4.12). The visit need not identify conditions on rooftops, under floors or behind walls (E1527-21, 9.2.4); limits on what was seen are recorded (E1527-21, 9.2.6).

What the federal rule says

Of buried generator tanks, the tank rule says:

UST systems that store fuel solely for use by emergency power generators installed on or before October 13, 2015 must meet the subpart D requirements on or before October 13, 2018.

40 CFR 280.10(a)(1)(ii)

The inquiry rule, 40 CFR part 312, lists among the records to review for the subject property

storage tank records and permits

40 CFR 312.26(b)(2)

How it is written up

A tank identified at the subject property is described in the report (E1527-21, 9.4). It becomes a finding when the professional judges it may indicate presence or likely presence at the subject property, and the opinion reasons for or against calling it a REC (E1527-21, 12.5, 12.6).

Where the professional concludes a release has occurred or is likely, the opinion gives the grounds: what was observed and what the records show. 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 the tank's condition poses a material threat of a future release, the opinion says what was observed and why. That REC is listed in the Conclusions as well (E1527-21, 3.2.52, 3.2.73, 12.7).

Where the professional concludes neither, the opinion gives its reasoning on the same four facts (E1527-21, 12.6). Whether the tank meets the tank rule is regulatory compliance, outside the standard's scope unless the user adds it (E1527-21, 13.1.2, 13.1.5.14).

The generator room, vault or yard that holds the tank may be what could not be observed on the site visit. 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.