SOUTH PORTLAND — A citizens group that opposes the prospect of tar-sands oil being pumped through South Portland has collected nearly 4,000 signatures to ask voters whether they want to ban oil importation within city limits.

The 3,779 signatures are nearly four times the 950 needed to put the question before voters on the November ballot. The question would ask whether the city should enact a zoning change to restrict new development of petroleum-related industry on its waterfront.

“It’s clear the people of South Portland want this initiative in November,” said Carol Masterson, an organizer with the Concerned Citizens of South Portland.

Mayor Tom Blake and his wife, Dee Dee, were the last to add their signatures to the list Monday, in front of a small crowd outside City Hall.

Blake acknowledged that the pipeline’s owner, Portland Pipe Line Corp., has provided jobs in the city. But he punctured the notion that employment opportunities could trump the values of environmental safety and long-term energy sustainability.

“No amount of jobs are important (enough) if we can’t drink the water, breathe the air or work the soil we stand on,” Blake said.

Tar sands oil is heavy crude oil from deep underground sand deposits. The largest deposits, which are flushed from the ground with steam, are in western Canada.

Environmentalists have campaigned to stop its movement, because of fears about spills and concerns that burning the fuels derived from it would drive up carbon emissions and accelerate climate change.

Petroleum industry representatives say that transportation of tar sands oil by pipeline poses no public safety hazard.

The citizens group in South Portland says any pumping of tar-sands oil through the city’s port would require construction of two smokestacks near Bug Light Park that would emit an unknown combination of volatile organic compounds and other harmful gases and particles.

In a prepared statement, Portland Pipe Line Chief Executive Officer Larry Wilson said the company “intends to be pro-active in its response” to the proposed ordinance.

Company spokesman Ted O’Meara said previously that the ballot initiative unfairly targets a company that has consistently provided jobs and tax revenue for the city, as well as other benefits.

“Should we decide to develop our facilities further we have every confidence that the City of South Portland and other agencies would treat us fairly and consistently as they have in the past,” O’Meara said in a prepared statement. “In the meantime, we ask that the community not discriminate against one of the top taxpayers and job creators in the city.”

There is no proposal now to reverse the flow of the Portland-Montreal pipeline, which has sent crude oil through 236 miles of underground pipe into Canada for processing since the middle of the 20th century.

Although a previous proposal to use the underground pipe to move tar-sands oil out of western Canada was abandoned in 2008, the prospect has sparked enough interest and objection for the pre-emptive ban.

Proponents of the ordinance said that, to ship tar-sands oil from South Portland’s waterfront, new equipment would have to be installed near the piers to handle and process the heavy oil, including two smokestacks that would emit the byproducts of handling the oil and preparing it for loading into tankers.

The proposed ordinance would more strictly define what is allowed, and specifically bar the unloading of crude for shipping north as the only permitted use in the waterfront zone. Supporters say the approach is backed up by case law and would stand up in court if oil companies challenged it.

As long as enough signatures are verified, the South Portland City Council is expected to take up the measure in July and hold a public hearing before it decides how to proceed.

The councilors could amend the zoning language, vote to adopt it as proposed and preclude a citywide vote, or let residents decide in November without changing the proposal. Blake said he expects the proposal to be sent to the ballot.

“The number of signatures speaks volumes,” he said.

Matt Byrne can be contacted at 791-6303 or at:

[email protected]