I think you can safely say that the ants you found are not fire ants. While the brave and slightly unwise are willing to poke a fire ant nest with a stick, I doubt that any local would do that with a bare hand more than once anyway.

The first point is that they sting and it hurts a lot for a week to a year and several stings would give you a medical visit. AND they are agressive.

Second, they live underground but build tall mounds, probably over an inch high. However there are little black ants that build small mounds too.

Here is what I wrote a couple of years ago:
The North Carolina ag extension agents have been giving classes in fire ant removal for a year or so. The gist of the class is the following.
The effective way to remove fire ants is to poison the ants with any of the slow acting types that slowly get carried to the whole colony including the queen. This completely removes the colony AFTER A FEW WEEKS. Generally these are distributed around but not on the hill on a warm day when the ants are foraging. Put a potato chip near the mound if in doubt; if the ants don't show up in 30 minutes they won't be around to pick up the poison until it gets damp and unappatising.
Also important; one should not indiscriminately poison all ants. Other ants are teritorial and will fight to keep fire ants away. They are your friends!

and- the poison is poisonous to birds, too- so best to cover it up lightly with tarps and such til it's gone so as not to poison your local birds. I've found if don't want a fire ant nest somewhere, if i rile them up good, they'll move elsewhere. I tolerate them in my garden b/c i have lots of good ants and i don't like poison. Just be aware of where they are. They do like to get into potting soil, but if you discover a pot with them in it, bang and thump it around good and really soak it a couple times and they are likely to relocate. They don't like being disturbed. Of course if you don't have them, keep an eagle eye and get the first mounds with poison and you'll remain fire ant free. But once they're around, it's hard to totally control them.
One method that's supposed to work is to take a shovel full from different mounds while it's still cool and let them fight it out. There's some controversy about that though, b/c they form huge colonies and while it may look like a bunch of different nests, they are probably connected.

This is a proven ant deterrent that Ann Landers' sister, Abigail Van Buren, once recommended in "Dear Abby," her syndicated column, now written by her daughter: Take a piece of chalk, like that used in school classrooms with chalkboards before the advent of today's electronic smartboards, or whatever they're called; and draw a heavy circle of chalk around whatever you want to keep the ants out of. Except for an occasional rogue ant, or scab, those little pismires will not cross that chalkline. Try this method instead of polluting your corner of the universe with chemicals.