After three summers of enduring a torturous, nonstop buzzing noise from a nearby office building, residents of a tree-lined Vienna neighborhood opened their windows, returned to their decks and dined al fresco for the first time this past weekend. The FBI’s Terrorist Screening Center on Follin Lane completed the replacement of its noisy rooftop cooling towers and will soon install screens that should make the building’s ambient noise vanish, as promised by FBI officials last year.

“We in the neighborhood feel sort of like we are emerging from our bunkers after an extended siege,” said Ken Foley, a nearby resident who helped marshal nearly three years of citizen resistance against the agency. “We can actually open our windows in the evenings and in the mornings and even during the day, and hear the song of birds and frogs and insects instead of the helicopter-like drone of the cooling fans.”

Residents of the neighborhood just east of Route 123 had been tormented by the low-level drone since the summer of 2010, even before the FBI moved in as the only tenant of a building owned by the Goldstar Group of Bethesda. The town of Vienna threatened to withhold the agency’s occupancy permit if the noise — something like a helicopter hovering a block away, or several lawn mowers, 24 hours a day — wasn’t reduced.

Town officials said the FBI promised to fix the buzz, and the Terrorist Screening Center opened for business in November 2010. The center tracks terrorists and maintains the no-fly list, among other duties. Neighbors said the previous tenant, the CIA, was notably quieter.

But the insistent hum remained, through the summer of 2011 and then into last year, when residents and town officials really became outraged. For all of the center’s computing power needs, the renovated building had 23 “dry cooler” glycol-based air conditioning units installed on the roof, each with 10 high-speed fans, for a total of 230 fans operating almost continuously.

An architectural rendering of the Terrorist Screening Center in Vienna was submitted in 2011 to obtain approval for two memorials for the Sept. 11, 2001, attacks. The air conditioning units on the roof were omitted from the rendering. (Hickok Cole Architects - Town of Vienna council records)

But in July, shortly after a story in The Washington Post, Terrorist Screening Center director Tim Healy and his staff stood in the neighborhood of Niblick and Mashie drives and heard what all the complaining was about. Foley said Healy told him “he had not previously realized just how loud the noise was. He looked me in the eye and he shook my hand and he assured me that the problem would be fixed and that it would be fixed sooner rather than later.”

So the FBI and its property manager, the General Services Administration, set about obtaining the permits and clearances from the town of Vienna to install new cooling towers and new screens. The new system should save taxpayers money by using water instead of glycol, the FBI told Foley.

Vienna Mayor Jane Seeman said she was “not quite ready to breathe a sigh of relief. The screening walls are being built this week and there have been no sound checks made at this time, so I am happy but cautious.”

Mafara Hobson, a spokeswoman for the GSA, said her agency and the FBI worked together to install “a much quieter and more sustainable water-based cooling tower at the facility. We were committed to solving this issue, and even more pleased to be able to do so in time for summer.”