SOUTH PORTLAND — Residents urged city councilors Wednesday night to fight a proposed liquefied petroleum gas depot at Rigby Yard in South Portland and force NGL Supply Terminal Co. to look for another site.

While city officials promised to shepherd the NGL proposal through a rigorous review in the coming weeks, councilors considered enacting a six-month moratorium to allow thorough study of the depot’s potential public safety, economic, environmental and legal impacts.

NGL wants to build a propane depot at Rigby Yard to replace its existing terminal on Commercial Street in Portland, where the state is expanding the International Marine Terminal. The proposal is on track for a Planning Board hearing in December at the earliest and NGL needs to leave the Portland site before next spring.

Residents expressed concern about the potential for a catastrophic explosion if the depot were built at Rigby Yard, a 245-acre industrial site that sprawls between the Cash Corner and Thornton Heights neighborhoods off Route 1.

Joyce Mendoza lives on Thirlmere Avenue, a half-mile from the proposed 10-acre depot site. She said it poses an “unacceptable risk” to people who live near the rail yard.

“Eventually, something will go wrong,” said Mendoza, one of a dozen residents who spoke against the proposal during a council workshop at City Hall.

Michael Pock of Grand Street was one of two residents who spoke in favor of the proposal, saying that the opponents were using scare tactics because they don’t want the depot in their backyards.

“You people are afraid of your own shadows,” Pock said, adding that he has faith that the fire department can ensure the safety of the proposed depot and surrounding neighborhoods.

The NGL proposal has been a source of mounting tension in the community and on the council since the company submitted a preliminary plan in February.

A downsized formal proposal submitted last month reduced the maximum amount of propane that could be on the site in fixed storage tanks or queued-up rail tank cars from more than 1 million gallons to upwards of 744,000 gallons.

Councilors Tom Blake, Brad Fox and Patti Smith spoke strongly in favor of enacting a moratorium on fuel storage facilities, which would require support from at least five of the seven councilors.

“I think it’s very reasonable for us to take six months,” Blake said, to better understand a complicated proposal, consider stricter fire protection ordinances and research federal railroad laws that may preempt the city’s intervention.

Fox spoke more forcefully, saying “We don’t need any new tanks and we don’t want any new tanks.”

Councilors Melissa Linscott, Maxine Beecher and Mayor Linda Cohen expressed concern about the lack of a clear reason for a moratorium.

Councilor Claude Morgan staunchly opposed a moratorium, saying that people are “hoping to kill the project,” and warned that the city cannot afford another lawsuit. South Portland has been sued by the Portland Pipe Line Corp. over an ordinance the council passed last year to block tar sands oil from flowing into the city.

Morgan also said he was “disturbed” that the council has been conducting unannounced meetings on the NGL proposal for several months via mass emails sent to all councilors.

“We are ripe for a lawsuit,” Morgan said. “We have to be careful what battles we fight. This is not the battle for me.”

Councilor Fox said he believed the mass emails were protected free speech that shared information about the NGL proposal.

The council took no vote on the proposal or moratorium. Another workshop on both is scheduled for Nov. 9.

City Manager James Gailey said during the meeting that NGL has agreed to reduce the number of filled rail tank cars that would be allowed to queue up at the depot from 24 to 16. That would further reduce the depot’s total capacity to just over 500,000 gallons, including one fixed, 24,000-gallon storage tank.

Asked about the economic benefits of the NGL proposal, Gailey said, “I’m not seeing a lot of benefits as it sits.”

Fire Chief Kevin Guimond is one of several city officials who are reviewing the proposal. He assured residents and councilors that he’s researching best practices nationwide and won’t be issuing a report for several weeks. “I’ll take all the time I need,” Guimond said.

NGL is a subsidiary of NGL Energy Partners of Tulsa, Oklahoma, which includes Brunswick-based Downeast Energy. The company’s 4-acre facility in Portland has fixed storage for 280,000 gallons of propane and track capacity for eight cars.

NGL representatives handed out a written statement at the meeting touting a clean safety record and a willingness to work cooperatively with city officials and operate “a smaller, more efficient facility that complies with all existing city ordinances and fire safety codes.”