# About ust-ct — scope, sources and limits

> How this site is built: which files are joined, what is deliberately not published, and what the records cannot say.

## How this site is built

An independent search layer over six public files. Not affiliated with the Connecticut Department of Energy and Environmental Protection.

### Six files, joined on one identifier

The Department publishes tank details, contacts, compliance, enforcement,
releases and an active-facility list as separate datasets, all keyed on
`agencyfacilityid`. This site loads all six and joins them.

The join rates were measured before anything was built, not assumed:
contacts **99.7 %**, compliance **99.9 %**, the
active list **99.9 %**, enforcement **99.9 %** on
its own `relatedfacilityid`, releases **95.6 %** on
`ustid`.

And one that failed: `lustid`, in the releases file, looks like a
facility identifier and matches **0 %** of them — it is a
different sequence entirely. Had we assumed it, releases would have attached
to nothing, and no audit would have caught it.

### ⚠️ What no page here says

**That a site is polluted.** Not one of the six files carries a
concentration, a volume, a depth or an extent. Every figure on this site is a
count or a date. [What each record actually is](/records.md).

**The names of contacts.** 12,749 facilities have people on
the record as responsible for them. Those names are natural persons’
names; they appear only on an individual result, drawn in your browser from
the part of the URL after the `#`, which cannot be indexed.

**A list of facilities with releases or red tags.**
2,561 and 1,593 addresses respectively. Under such a heading they
would read as a verdict on each. The counts and their distribution are
published; the individual record is one search away, with its dates.

### ⚠️ Two corrections worth recording

The first draft of the loader asked for columns named
`tankinstalldt` and `tankclosedt`. The file calls them
`installationdt` and `tanklastuseddt`. The result was not
an error but a *silence*: the installation date came out empty on all
12,749 facilities, and an absent field looks exactly like a badly filled
one.

Finding that also found the field that matters most —
`tankconstructioncd`, which is what a tank is made of, and the only
physical risk signal these files carry. [Why it
matters](/steel.md).

### How the pages are chosen

A town gets a page at 30 facilities (102 of
264 place names qualify, covering 85.3%); a
town-and-substance page needs 40; a substance page
80. Every facility sits in exactly one town and one principal
substance, so crossed pages divide their parent rather than overlapping
it.

### Sources

Six datasets from the Connecticut Department of Energy and Environmental Protection on data.ct.gov, all public domain, all
refreshed weekly. Our copy is from **2026-08-21**. For
anything a transaction depends on, use
 the Department’s own
records .

The Department publishes these six files as public-domain open data and refreshes them weekly. They record that a document exists — an inspection, an action, a reported release — and carry no measurement of soil, water or extent. Nothing here is an environmental assessment.

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Página: https://ust-ct.pages.dev/about/
Fonte: Underground storage tank records — Connecticut Department of Energy and Environmental Protection (six datasets)
Recolha: 2026-08-21