There's a slam-dunk easy answer for that. Get some beneficial nematodes
and apply them after the next good watering or soaking rain. Do it in the morning or evening so they don't get the brightest light or the heat of the day. Here is Howard's latest list of where to get various beneficial insects and nematodes
For the specific mounds, you can use the mound drench
recipe and treat them until you have a chance to get the nematodes.
You can also do nematodes on specific mounds, and that is a good idea (the amount of mixture you use varies whether you broadcast to the entire space or treat just mounds) but since your entire yard has ants, I think I would use the package on the entire yard the first time, and treat individual mounds with the mound drench, and perhaps come back a few weeks later and treat any remaining mounds with the more dense mix of nematodes recommended for tough mounds.
Or you could do the opposite. The thing about organic gardening is that there are lots of ways to do it and the choices you make depend on what you have available to you as far as the materials called for.