Wed., Sept. 20, 2006 Link To Herald The Halifax Herald Limited

Tar ponds could have concrete solution

Engineers, students exploring how best to stabilize polluted Sydney site


Sydney - The discussions centred on the molecular structure of organophilic clay but the goal was cementing relationships as 130 delegates and students delved into the science of using concrete to clean up the Sydney tar ponds during a workshop Tuesday.

"We are excited by the interest people have shown. They are here to see what is happening and to talk about the possibilities," said Rick Joseph, executive director of the Nova Scotia Environmental Industry Association, the group that organized the three-day conference in Sydney.

The delegates, experts in using cement powder to create a solid covering to solidify and stabilize chemicals in contaminated soil, have come from across Canada, the United States and Britain, Mr. Joseph said, speaking at Cape Breton University.

The Sydney Tar Ponds Agency proposes to use the solidification and stabilization method to clean up a portion of the site, a remnant of 100 years of steelmaking in Sydney. It is estimated that 100 million tonnes (* see correction below)
of highly toxic PCBs, PAHs, heavy metals and solvents such as benzene, toluene and formaldehyde remain in the soil.

On Tuesday, as engineers in suits sat side-by-side with students outfitted with eyebrow rings and lip piercings in a university lecture hall, researchers from Halifax, Massachusetts and the United Kingdom delved into such things as how additives like activated carbon and clay will interact with chemicals like those found in the soil at the Sydney tar ponds and coke ovens site.

Dalhousie researcher Pak Yuet said the molecules of many contaminants continue to move and need to be immobilized before a solid covering is created at the site. His slide, showing clay molecules and contaminants mixing, was reminiscent of a TV commercial that showed animated scrubbing bubbles cleaning a bathroom.

Kristine Carbonneau, a scientist with the Westford, Mass.-based environmental consulting firm ENSR, addressed concerns raised by a panel review studying the proposed cleanup suggesting that seawater could react with the cement, causing the concrete barrier to crack and allowing contaminants to leach into the soil.

"While there could be a small-scale loss of strength, the contaminants are not going to come flooding out," she said, responding to a question from Cape Breton Regional Municipality councillor Vince Hall.

After the presentation, the councillor told The Chronicle Herald that hearing the science of the cleanup had helped remove politics from the highly-politicized cleanup issue. "The presentations have been very candid. They are addressing the risks upfront," he said.

For Mr. Joseph, the conference is a step in the cleanup process. He expects to have a similar gathering once work is well underway at the tar ponds site.

"I think the process is moving forward. In another few years, we'll see people's faith come back. Then their health and optimism will improve and optimism will grow within the community and they will see . . . we can solve our own problems."

Conference participants will tour the tar ponds site today before the workshop wraps up.


* Estimates vary from 700,000 tonnes to 1 million tonnes, not 100 million tonnes as reported in the article above. - Correction by Dan McMullin - Sept. 20, 2006