SOUTH PORTLAND — The City Council gave final approval Monday to a controversial fire code amendment that requires a 1,257-foot buffer between important public facilities and any liquefied petroleum gas distribution plants that might be proposed in the future.

The council’s action followed last month’s announcement by NGL Energy Partners that it had withdrawn a year-old proposal to build a $3 million propane depot at Rigby Yard, which is owned by Pan Am Railways.

The council voted 4-3 on the buffer requirement despite concerns that it could draw legal action by Pan Am because the amendment might by viewed as an infringement on federal pre-emption rights that allow railroads to disregard many local regulations.

“It’s not an invitation to come and sue us,” said Councilor Eben Rose, who voted in favor of the buffer along with Councilors Patti Smith and Brad Fox, and Mayor Tom Blake.

Smith said the amendment “is a declaration of what we care about” and want to protect in the event of a potential explosion.

Councilors Linda Cohen, Maxine Beecher and Claude Morgan opposed the buffer, saying that the city cannot afford a second major lawsuit. The city is currently in federal court defending its Clear Skies ordinance, which the Portland Pipe Line Corp. is challenging because it blocks crude oil exports.

“I can’t see putting another ordinance out there that raises a red flag,” Cohen said.

Blake acknowledged that the amendment had taken a “troubled, long path” to approval. He blamed city staff for deeming NGL’s initial application complete when it wasn’t and the council for getting sidetracked by a failed propane moratorium effort.

The 1,257-foot buffer is the minimum safe distance recommended by the U.S. Department of Transportation for first responders at emergency incidents involving rail cars that contain propane, according to the amendment.

The buffer applies to 19 different types of public infrastructure, including all government buildings, community centers, police and fire stations, hospitals and nursing homes, schools and places of worship, piers, boat ramps and public beaches, power plants, public utilities and telecommunications services. The only residential properties listed in the amendment is housing for senior citizens, veterans and people with disabilities.

The fire code amendment was drafted by citizens and largely rewritten by Russell Pierce, a member of the Portland law firm Norman, Hanson & DeTroy.

Pierce has said that while federal pre-emption laws prevent municipalities from passing zoning regulations that infringe on railroad activity, they appear to allow objective local regulations that protect public health and safety, such as fire codes.

While the buffer requirement would have blocked NGL’s proposal because of its proximity to the Cash Corner Fire Station, it appears that a large, outer section of the 245-acre rail yard remains open to potential development of a propane depot.