"Regular" gasoline (87 octane much of the US, lower in the western states) was (is?) a commodity. What one bought at the pump was whatever 87 octane was available at the depot, regardless of the brand of the station.
High-octane (93 in much of the US, lower in the western states) is brand-specific. Pipeline loads are measured using clocks and flow-rates. E.g.: from 12:00 to 12:05, it's Brand X Ultimate. The pipeline flow-rate is used to determine what's in the line at the various depots.
The head and tail of the load are mixed, but if the high-octane is in the middle of a regular gas run, it's likely not a big deal. I don't know if it winds up in the purge tank or just a part of the other runs.
The intermediate grades were (are?) mixed at the station between high-octane and regular.
The article claims that, when a station offers Top Tier gasoline, it must do so for all "levels" of gas they provide, so your "regular is the same and the others are differentiated" interpretation doesn't match up.
My answer was to the commenter's questions, which, to me (perhaps incorrectly), did not involve the article's discussion of "Top Tier" gas.
As you point out in the article, a Top Tier gas licensee must meet the standards for all levels of gas they provide.
What the article doesn't make clear (to me), is that Top Tier is a set of standards that is licensed to almost every brand in the US (toptiergas.com). Being "Top Tier" doesn't mean the regular is Station Brand specific, just that it meets the Top Tier standards.
Given the large list of brands, it would not surprise me if most (or all) regular gas produced in the US meets these standards and is what you get at the depot as a commodity.
But I do not know that and my other info may be out of date. Hopefully there's a active pipeline worker / gas hauler reading :)
I assumed the "Top Tier" ingredients could be lumped together with other stuff, like ethanol (the street view scene linked in my original question shows a tank labeled thus), octane-boosting additives, detergents and so on. All based on the totally generic "regular gasoline" - two of the giant tanks are labeled that but there are a few tanks further back whose label is not visible.
The pipeline map shows the pipeline terminating pretty much exactly where you can see it coming out of the ground. There are other fuel depots nearby. One assumes secondary pipes to deliver material to them, but I don't know this business at all, so the more people who know do pipe in, the better.
Ah, one of the other fuel depots has some tank labels visible as well, and it does have separate tanks for "regular" and "premium" gas.
"Regular" gasoline (87 octane much of the US, lower in the western states) was (is?) a commodity. What one bought at the pump was whatever 87 octane was available at the depot, regardless of the brand of the station.
High-octane (93 in much of the US, lower in the western states) is brand-specific. Pipeline loads are measured using clocks and flow-rates. E.g.: from 12:00 to 12:05, it's Brand X Ultimate. The pipeline flow-rate is used to determine what's in the line at the various depots.
The head and tail of the load are mixed, but if the high-octane is in the middle of a regular gas run, it's likely not a big deal. I don't know if it winds up in the purge tank or just a part of the other runs.
The intermediate grades were (are?) mixed at the station between high-octane and regular.