I used to do the grounds for a church and would throw down some powder I'd found(which I've forgotten, but I'll look around) & Amdro, together.
I literally could police the grounds @7am on a Sunday morning, powder & bait the rock lawn for fire ants around the play areas and by 8:30 not an ant to be found and stay clear of ants for a couple of weeks.

I found your park.

I hope fire ants are dying back.
I went to a church picnic a couple of years ago, in a field just outside of Nacogdoches, and the fire ants absolutely made it impossible to stop moving.
A person could not just stop, stand and converse without the ants attacking, and as the afternoon wore on, with 40 or so people tramping around, it just got worse & worse. The property owner was a botanist at the local university and had this peach orchard where the picnic was. He'd become convinced that the ants were developing immunity against the common ant killers.