Politicians travelled to Sydney, N.S. to announce their $400 million plan for ending the blight of the tar ponds, one of Canada's most notorious toxic sites.

"After many years of discussion and study, an agreement has been reached on an approach to clean up the Sydney tar ponds and coke ovens," Sen. Michael Fortier, the minister of public works, said Sunday in Sydney.

The site is polluted with about one million tonnes of sewage and toxic industrial waste left behind after decades of steel-making.

During a news conference Sunday in the Cape Breton community, government officials of all levels, including Foreign Affairs Minister Peter MacKay, announced that the ponds would undergo stabilizing and solidifying.

"The tar pond is a giant soupy mess, and they're going to shore it up with concrete and put up retaining walls to make sure it doesn't leak any further and then they can go about the task of cleaning it up," CTV Atlantic's Toby Koffman told CTV Newsnet.

Once the ponds have been contained, new layers of clay and soil will be placed on top.

Fortier said this approach is preferable to incineration the toxic stew.

Officials said once the process is complete in about seven years, the toxic ponds should not produce any adverse health or environmental affects -- though the 100-hectare site will remain under constant observation.

Local residents and environmentalists were relieved to hear the $400 million cleanup didn't involve incineration of the sludge.

However, a small group of protesters, who had been kept away from the announcement, claim the technology has not been tested.

"It's a serious mistake and we fear we are going to waste $400 million in another politically motivated boondoggle," said Bruno Marcocchio of the Sierra Club of Canada.

His group said there should have been provisions to move nearby residents.

"I know there's always skeptics from some sectors of society.  but we are moving forward on solid recommendations," MacKay said.

"This concerns me because if this technology doesn't work the way they tell us it will, then our future generation is going to have to dig it all up and go back in there," resident Eric Brophy told reporters.

"But I'm hoping not, I'm hoping this will work."

Cape Breton Mayor John Morgan was also skeptical.

"What the province of Nova Scotia has done is steered the cleanup to the very cheapest mechanism possible with no plan for future use of the site and really tenuous science,'' he said.

"All of this is based on a threat that if we don't accept this, they will light up a PCB incinerator in the middle of the city.''

The announcement was the fourth proposed plan since the 1980s.

The release of the plan comes after roughly 20 years of debate, consultation and complaints from people who live in the area.

The neighbourhoods that surround the site on three sides have unusually high rates of cancer.

With a report from CTV's Toby Koffman and files from The Canadian Press