Or if you must blow towers against the building, better make sure you have the best chemical treatment guy in town!
Towers at my plant are below grade and blow up through grates just like in your pics. But there's no white chalky residue on the grates or anywhere else. Other towers in town I've seen do just like in your photos. I have the best water treatment guy in town...good water treatment pays in so many ways!
Building Physics Rule #1: Hot flows to cold.
Building Physics Rule #2: Higher air pressure moves toward lower air pressure
Building Physics Rule #3: Higher moisture concentration moves toward lower moisture concentration.