Last week, I wrote about how residents of Casco in a special town meeting voted up a nonbinding resolution against the transportation of controversial tar sands oil through their community.

Now, Maine’s largest city is following in its footsteps, with a vote planned by the city council tonight on a policy that would bar Portland from buying any oil-based fuels from refineries that process tar sands.

The proposed policy is rooted in concerns that the Portland-Montreal Pipe Line may be reversed by the oil companies in its ownership parentage so as to accommodate the transportation of tar sands oil from Alberta, Canada, to the international market via the port of Portland. Currently, less controversial oil is brought into the port from tankers, and it’s piped the other direction up through the state and into our neighboring country to the north.

Here’s a graph I filed in my post about Casco to describe environmental concerns about tar sands oil, which are more acidic and gritty than most crude oil, and which environmentalists feel is dangerous to pipe through aging lines like the 62-year-old Portland-Montreal Pipe Line:

One incident that is often referred to by opponents is a 2010 spill of bituminous oil in the Kalamazoo River in Michigan that environmental regulators said has “permanently” polluted 38 miles of the waterway and — at one point — raised benzene gas levels in the nearby air to 15,000 parts per billion. The exposure level at which humans can be severely harmed or killed, he said, is 9 parts per billion

I always have to mention when writing about this topic that representatives of the Portland Pipe Line Corp., as well as the Maine Department of Environmental Protection, have said there are no imminent proposals to reverse the flow of the pipeline. And even if there were, the pipeline managers have said, the reversal could mean only that they plan to transport less controversial crude oil from western Canada.

Tar sands oil remains a hot topic nationwide in part because of the proposed Keystone XL pipeline, which earlier versions were plotted to run through sensitive Nebraska Sandhills, and which has been hung up by the Obama administration because of environmental concerns.

At a news conference held this morning in Portland, Mayor Michael Brennan was joined by city councilor David Marshall as well as representatives of Environment Maine, the Sebago Lake Anglers Association (the pipeline passes by the lake), the Natural Resources Council of Maine and others to preview the council consideration tonight.

A petition requesting the policy was signed by 2,475 Portlanders, according to a release today by Environment Maine, the group which handed it in to city officials.

Portland Mayor Michael Brennan (BDN file photo by Robert Bukaty)

Some statements on the proposal, first from Brennan:

Tonight’s policy, which seeks to eliminate the use of polystyrene, water bottles, and tar sands oil in city operations, is the latest step towards reaching our sustainability goals. As Maine’s largest city, we have a responsibility to lead and demonstrate to others that by enacting reasonable policies we can make a real difference in the effort to halt climate change and reduce greenhouse emissions.

David Marshall (BDN file photo by Joel Page)

David Marshall:

The Portland City Council is poised to be the first on the east coast to adopt a purchasing policy restricting tar sands oil. We have worked hard to reduce our municipal carbon emissions by more than 30 percent. Restricting the use of tar sands, the most carbon intensive oil in the world, is consistent with our long standing carbon reduction goals.

Emily Figdor (BDN file photo by Seth Koenig)

Emily Figdor, director Environment Maine:

Tar sands oil is dirty, dangerous, and doesn’t deliver for Portland. Just imagine cleaning up a tar sands spill on a winter day like today. Thousands of Portland residents have signed our petition, and we urge the City Council to protect our city by making Portland tar sands-free.

Dylan Voorhees (BDN file photo by Troy R. Bennett)

Dylan Voorhees, Natural Resources Council of Maine:

Portland and tar sands are incompatible. Tar sands is one of the dirtiest sources of energy on the planet, while Portland is proudly one of the greenest cities in the country. Fuel from dirty tar sands should have no place in municipal buildings and vehicles, and we urge the City Council to pass this resolution to make sure that never happens.

Others who weighed in with statements in today’s Environment Maine release included Bob Klotz of the organization 350 Maine, Danielle Droitsch of the Natural Resources Defense Council, Aaron Sanger of the group ForestEthics, and Eliot Stanley of the Sebago Lake Anglers Association.

Update (Jan. 24, 2013, 10:18 a.m.): Here’s what my BDN blogger colleague Carol McCracken wrote about the council meeting that took place after this news conference. Carol wrote that the council sent the proposed policy to a subcommittee for review. Read more about that here.