MILWAUKEE -- General Mitchell International Airport is closed due to standing water on the runway. Friday, July 23, 2010.Airport officials hope to have the airport reopened by 2 p.m. Friday.Frontier Airlines customers who were scheduled to travel on Friday, and those who have already begun their travel, may make one itinerary change without incurring the standard change fee. This change must be made by midnight, July 24, 2010, and travel must be completed by Aug. 6, 2010. This poli...