Ant hills everywhere!

We recently had our backyard graded after building an addition to our house. We plan to put down sod in the next month (once we can get rid of some of the rocks and roots that are now showing up). In the last few weeks, there are ant hills appearing daily. Many ant hills. What is the best way to get rid of them at this stage? Would a liquid spray work better than a granular bait? I am going to use a barrier treatment around the house, but feel I need to do something on the hills themselves. All the rain we are having isn't helping matters, either.