The trailer you are seeing on the station lot is called a "Remediation Unit" it is brought in to remove gasoline from the ground water under the station.
Stations today have "Test Wells" drilled into the ground in various places around the station. (Look for a 12" - 16" steel plate on the drive with a black triangle that says "Monitor Well")
These are checked periodically.
If you look around as your are driving, you will see these units on many old station lots. They are usually in the back somewhat out of site. Some are actual small buildings and not trailers and look like a small storage shed. They will all have a vent pipe sticking out somewhere.
If a presence of gas is detected, the wells are hooked together with a pipe and that water circulated thru a unit in the trailer separating the gas from the water. I don't know the exact process for doing it, but am sure if you Google "Remediation well" on the net, it will get you some info.
Once you can identify these units, you may see them setting on the lots of other business's as well. They are a sure "Clue" that a gas station once stood on that lot. We have an Arby's here in Speedway that has one. I faintly remember that over 20 years ago there was an old gas station that once stood there. Old Stations had Steel tanks and many of them leaked underground for years. It can take years for those units to clean up from those leaks.
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As for the warmer gas. Many stations today have such a high sales rate for product in their tanks, the gas does not have time to cool to underground temps.
When I load a load at the terminal. My gallons are temperature corrected at the time of loading. Stations today in my area also temperature correct for product being sold. Computer monitors make it a lot easier for this to happen. I think before they used a base standard for underground temps.
There was an article in a trucking magazine last year, where a chain of Truck Stops was caught "Heating" their diesel. That would probably only pay off on a large volume like a truck stop. Will see if I can find the article.
Chuck
