Underground storage tank closed in place

An underground storage tank (UST) at the subject property is out of use and still in the ground: filled or otherwise closed in place, or only shut down. The tank being there does not settle whether there is a recognized environmental condition (REC). That depends on four things: which kind of closure the tank had, what was measured at closure, whether the tank still holds product, and whether anything points to a release.

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 what the kinds of closure are; it classifies nothing under the standard.

Which kind of closure. Part 280 has two. In a permanent closure the tank is emptied and cleaned, then taken out, filled with an inert solid, or closed in place in a way the implementing agency approves (40 CFR 280.71(b)). In a temporary closure the system stays under the rule: corrosion protection is kept up, and release detection too unless the system is empty (40 CFR 280.70(a)). When it lasts three months or longer, the owner and operator must "Leave vent lines open and functioning" and "Cap and secure all other lines, pumps, manways, and ancillary equipment" (40 CFR 280.70(b)). After more than 12 months of temporary closure, a system short of the rule's new-system or upgrade standards, spill and overfill equipment aside, has to be permanently closed unless the agency extends the period, and a site assessment comes before any request to extend (40 CFR 280.70(c)).
What was measured at closure. The assessment is owed whatever the method: before a permanent closure is complete the owner and operator measure for a release at the place where contamination is most likely, taking the method of closure into account (40 CFR 280.72(a)). The same paragraph treats the assessment as met where vapor or groundwater monitoring, run as the rule's release detection, is operating at closure and shows no release. For a system closed for good before December 22, 1988, the rule calls for an assessment when the agency directs it (40 CFR 280.73). The results are kept in one of three ways: "By the owners and operators who took the UST system out of service", "By the current owners and operators of the UST system site", or "By mailing these records to the implementing agency if they cannot be maintained at the closed facility"; three years after closure is the only period the section sets (40 CFR 280.74).
Whether the tank still holds product. Product left in a tank may bring in the third part of the REC definition. A material threat is a threat that is obvious, that will probably end in a release, and that the environmental professional judges would probably harm public health or the environment (E1527-21, 3.2.52). For release detection under part 280, a temporarily closed system counts as empty with "no more than 2.5 centimeters (one inch) of residue, or 0.3 percent by weight of the total capacity of the UST system" left in it (40 CFR 280.70(a)). Ask when the tank was emptied and what filled it.
Whether anything points to a release. The standard's appendixes are nonmandatory. Appendix X4's note gives a bare steel UST installed decades ago with no leak detection as a possible example of a likely release, if the professional believes one has likely occurred (E1527-21, X4.1).

The records that bear on it

The registration and the agency file. 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). For a listed subject property the file should be reviewed, or the report explains why not (E1527-21, 8.2.3.1). Look for the agency's approval of the closure and the sampling results. Releases are a separate record, the leaking tank list. Ohio lists Closed in Place among its tank status codes. Georgia says the owner fills out a closure report whether the tank is removed or closed in place.
Documents and interviews. The owner, key site manager and user are asked whether they know of tank registrations, site investigation reports and cleanup reports (E1527-21, 10.8, 10.8.1).
Site visit. Vent pipes, fill pipes and access ways are looked for, with stained soil or pavement (E1527-21, 9.4.12, 9.4.23).

What the federal rule says

Of the ways a tank may be permanently closed, the tank rule says:

All tanks taken out of service permanently must: be removed from the ground, filled with an inert solid material, or closed in place in a manner approved by the implementing agency.

40 CFR 280.71(b)

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: the tank's age and construction, what the closure sampling shows, what was observed. 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 that product left in the tank poses a material threat of a future release, the opinion says 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 closure met 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 part of the subject property that holds the tank and its piping 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.