A Nova Scotia Supreme Court judge has ruled that some residents who lived near the Sydney tar ponds will be able to join in a class-action suit against the provincial and federal governments.

Justice John Murphy ruled Friday that only people who owned property or resided in a small area near the former Sydney Steel mill plant can take part in the suit.

The four representative plaintiffs — Neila MacQueen, Joe Petitpas, Ann Marie Ross and Iris Crawford — are suitable, Murphy said.

Lawyer Raymond Wagner had argued that thousands of plaintiffs should be included. He said anyone who had at least three years of exposure within a 5.6-kilometre radius of Victoria Road and Laurier Street in Sydney should be part of the class action suit.

Murphy, however, said that could include up to 50,000 people and would be unworkable. He instructed Wagner to narrow the parameters of his case.

Wagner said Friday that he plans to present the redefined boundaries within the next few weeks.

"He [Murphy] says this case should be certified, but the boundaries we've proposed are too big.," Wagner said "So, he's sent us home, basically to redefine the boundaries. If we get a boundary to circumscribe the most contaminated areas, then he'll certify the case — [he] has indicated that he'll do so.

"So, this is a major step forward. There is work yet to be done, but it is a major step forward."

The plaintiffs claim the governments knew about the health and environmental risks linked to the contaminated sludge in the tar ponds and failed to do anything about it.

"It is about the contamination of an entire community," Wagner said in court Monday. "It is about the dumping of dangerous and hazardous chemicals on the community, which we allege, that both defendants knew contained harmful substances."

The tar ponds, called one of Canada's worst toxic waste sites, is what's left from a century of steelmaking. Pollutants leaked out of a coke oven, the chamber where coal was heated, and about 700,000 tonnes of chemical waste and raw sewage accumulated over the decades.

The hearing was heard in Halifax earlier this week and was broadcast over the internet. About 400 people have signed up as plaintiffs to date.

Nine days had been set aside to hear arguments. With files from The Canadian Press