An environmental group has targeted what it considers Maine’s two most serious environmental threats in its annual “Dirty Dozen” list of polluters in New England.

One of the two has a long history in Maine while the other that has yet to establish one.

The Toxics Action Center, a New England grassroots environmental organization established in 1987, named the waste handling company Casella Waste Management Inc. among its 12 most flagrant polluters because of continuing issues surrounding garbage dumps and waste burning dating to the mid-1980s.

The other offender is still looming on the horizon – the proposed tar sands pipeline that some opponents say could prove to be a huge environmental threat.

Casella, which operates numerous landfills, dumps and incinerators around the state, has long been at the center of debates over the hazards posed by out-of-state toxic wastes and chemicals in landfills.

“The worst remain the worst,” said Tracie Konopinski, community organizer with the Portland office of the Toxics Action Center, a Boston-based nonprofit devoted to preventing and cleaning up pollution in New England neighborhoods and making communities more sustainable. Casella has appeared on earlier Dirty Dozen lists, she said.

“The threat long term (from Casella landfills and incinerators) is enormous,” said Ed Spencer of Orono Community Forums, who lives less than two miles from Casella’s landfill in Old Town and has been part of a citizen watchdog effort monitoring Casella’s operations in northern Maine. “They’re great at making promises, but they’ve failed to deliver.”

Casella officials could not be reached for comment Tuesday. The company has been negotiating with the city of Biddeford for the $6.65 million sale of the Maine Energy Recovery Co. trash-to-energy incinerator there.

Now operating in 14 states, Casella contracts for refuse pickup and transport, dumpster rental and recycling for residential, commercial, municipal and industrial customers.

Toxics Action Center also cited on its list the tar sands pipeline proposed to transport oil from Ontario, Canada, through the lakes region in southwestern Maine and on to Portland, where it could be shipped out by supertankers. The proposed pipeline represents a new threat to the state and region, Konopinski said.

“ExxonMobil’s tar sands pipeline is very worthy of this award,” said Emily Figdor of the environmental advocacy group Environment Maine. “Tar sands oil, the dirtiest oil in the world, could soon be coursing through an outdated oil pipeline that crosses the Sebago Lake watershed and ends in Casco Bay.”

Konopinski said the oil proposed for the pipeline is “more corrosive than conventional oil” and would present almost insurmountable problems in cleanup, should an accident or leak ever occur.

The Toxics Action Center suggests several measures for dealing with persistent polluters, including replacing toxic chemicals with safer alternatives, requiring polluters to pay for hazardous waste cleanup, ensuring that discarded resources are recycled, and pursuing renewable energy.

This year’s Dirty Dozen list is the first the organization has issued since 2007. It was culled from about 30 industries and businesses nominated by New England environmental groups, community leaders, public health officials, activists and residents.

Staff Writer North Cairn can be contacted at 791-6325 or at:

ncairn@mainetoday.com