Underneath a gas station animation - GIF

[Frank S]

One thing not shown in this animation is that most stations have a set of monitoring wells drilled in the area around the outside of the tanks so they can check for subterranean leaks before they hit the water table.

You can't see the bore holes but from .19- .25 you can see a network of conduits which would denote the probable connection to a perimeter network of sensors.