I have mentioned boiling water. It works but probably won't kill the mound in one application. This is evidenced by the thousands of dead ants that surround the mound, obviously carried by the hundreds of ants that didn't die.
Another method i have used is water drenching. This works in raised beds. You literally flood the bed. They may leave for drier soil.
John Dromgoole (natural gardener in austin) claims molasses will chase them off.
B-dahl bluestem is something rarely talked about. Something you'd plant as pasture grass. Someone walked several acres of bermuda and b-dahl and the ratio of ant mounds per acre was very different. Like 30 in bermuda compared to 1.5 in b-dahl. The reference indicated the seeds may be the reason, as the field can almost smell like death when it is seeding. It may be similar to paw paws, where flies do the pollinating vs
bees cause the smell it puts out.
Some times you have to cry uncle and buy something. Some products are biological, hitting only the ants. A little research
should point you to something acceptable when other options fail.