Warning notification "Air valves are treated as junctions with large surcharge depths."

Hi,

Again i got this warning notification stated above when i validated my model. Again i was not sure what this notification is really trying to tell me? It does not allow me to zoon into a structure, pipe, pond or anything so not sure where in my model that warning would pertain? Also not sure really if its another notification that means i need to fix something in my model. 

Again advise please. 

thanks,

Paola