The city of Boulder is suing the Federal Airport Administration (FAA) over a dispute on the potential closure of Boulder Municipal Airport. The city has accepted grants from the FAA in the past, which require the city to keep the airport open for a maximum of 20 years, according to the complaint. The cost of the litigation is expected to be $500,000 - $750,000, according to notes shared with city council. City council will vote on whether to approve pursuing the suit Aug. 8. The city attorney can seek retroactive approval from council in pressing circumstances, and the city manager and city attorney have both recommended approval.