SOUTH PORTLAND, Maine — The South Portland Planning Board on Tuesday found a proposed moratorium that would prevent tar sands oil from being piped through the city is consistent with the city’s comprehensive plan.

By a 4-2 vote after a meeting that lasted more than three hours, the board sent the proposed 180-day ban back to the City Council for final action.

Board members Sally Hasson, Caroline Hendry, Erick Giles and Kathleen Phillips voted in favor of the nonbinding opinion. It was opposed by Chairman William Laidley and member Fred Hagan.

Board member Rob Schrieber was unable to attend the meeting.

“I think we have more to lose by not taking the time to research things further,” Phillips said. “There are so many unknowns, we really need to do more research and understand what is exactly at risk.”

Hagan said the moratorium, presented at a City Council workshop the day after a proposed waterfront protection ordinance was defeated by voters last month, is “mediocre at its best”; Laidley said he is unconvinced an imminent threat exists to justify the ban.

In August, the Planning Board found in a 4-2 vote that the waterfront protection ordinance, which would have prevented the flow of tar sands by prohibiting expansion of petroleum industry activity on the waterfront, was in conflict with the comprehensive plan.

Tuesday’s finding sends the proposed moratorium, which specifically targets “development proposals involving the loading of oil sands/tar sands products onto marine tank vessels docking in South Portland,” back to the council with no suggested revisions.

A second council reading and vote are expected Dec. 16. Five councilors must vote in favor for the moratorium for it to pass. If passed, it will be retroactive to Nov. 6 (the date it was introduced) and could be extended another 180 days when it expires next spring.

The Planning Board deliberations and vote came after a public hearing that took about two hours, and during which Laidley unsuccessfully tried to steer speakers toward comments about the moratorium, as opposed to the dangers of tar sands oil or larger questions about how it is extracted.

As defined by city Corporation Counsel Sally Daggett at the beginning of the hearing, the Planning Board scope was to consider land use issues in the moratorium and its compatibility with the comprehensive plan enacted in October 2012.

“We are here solely to talk about the proposed moratorium and timeout,” Daggett said. She added any “substantive change” recommended by the board and accepted by councilors would require the approval process to begin anew, with a fresh first reading of a revised moratorium.

Public opinion from about 30 speakers at the hearing fell overwhelmingly on the side of moving the moratorium as written.

“The city can use the moratorium as the tool to answer a lot of questions,” Willard Street resident Richard Holt said.

Those opposed to the moratorium included Matt Manahan, the attorney representing Portland Pipe Line Corp., which owns the South Portland-to-Montreal pipelines that could be used to pump the diluted bitumen known as tar sands or oil sands to the city.

Manahan has called the moratorium unnecessary and possibly illegal, while maintaining the company has no current plans to import the oil for loading into tankers for export.

He also objected to preambles in the moratorium citing alleged health and environmental hazards found in tar sands oil.

“This is not the right vehicle,” he said. “It basically predisposes the outcome.”

Portland Pipe Line Corp. was granted a permit in 2009 to erect two 70-foot vapor combustion units needed for processing tar sands oil on a company pier near Bug Light Park.

The permit has since expired, and an emissions permit from the Maine Department of Environmental Protection good through next February was surrendered by the company in October.

U.S. Rep. Chellie Pingree, D-Maine, announced this week that the U.S. State Department will also review any renewed effort by Portland Pipe Line to reverse the flow of oil through the 236-mile pipeline that passes through Vermont and New Hampshire before terminating in South Portland.

Claims by Manahan and Portland Pipe Line Chief Financial Officer Dave Cyr that no plans exist to reverse the flow were doubted by speakers who support the moratorium.

“If Portland Pipe Line really had no plans, we have to ask ourselves why it would be paying a lawyer to come before you and ask not to pass this moratorium,” Angell Avenue resident Eve Raimon said.

If enacted, the moratorium would be accompanied by creation of a committee to look into health and environmental questions about tar sands oil.

“It would be my hope, if we do have a moratorium, that the oil people would be very much a part of the conversation,” Hendry said.