I imagine that a good way to get rid of a fire ant colony would be to spade deeply around the exposed mound slightly raising it and then saturating the exposed underside with a combination of wasp spray and liquid ammonia. I never tried it because that would be using the products in a manner inconsistent with their labeling and that would be a violation of federal law.
I would also have to surmise in my best guess that it would leave a brown spot in the lawn where grass wouldn't grow for probably 2-3 years, but that is just a guess since I would never try it, but I'd bet if I did it would pretty effectively kill off the entire colony.
Just an untried hypothesis.
would be to spade deeply around the exposed mound slightly raising it
:) excellent example of theory colliding with reality. You wouldn’t have the first spadeful up and the ants will have totally covered the spade and jumped onto you! Their rage upon attack is why lots of folks just ignite ‘em, then stand back and gloat.