Tar ponds could have concrete solution
Engineers, students exploring how best to stabilize polluted Sydney site
By JOCELYN BETHUNE
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
"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