By LAURA FRASER Cape Breton Bureau

Sydney - No one has a definite answer for Marlene Kane about why two parts of the cap surrounding the cooling pond at the Sydney tar ponds site have started to sink.

The agency managing the cleanup has not done a full investigation into what caused settling at the edges of the cooling pond, spokeswoman Tanya Collier MacDonald said Monday.

Agency officials have blamed the problem on melting ice but have not yet confirmed their hypothesis.

Ms. Kane has done research on her own into the work being done by the Sydney Tar Ponds Agency. Sinking soil just outside the cooling pond might foreshadow a future problem over the pond itself, she said.

"To me, this is a breach in the (cooling pond) cap and I just wonder how it will affect the sediments in the cooling pond that have been treated," she said. "Because there's a settling problem here with the cap, and a problem with the cap, (could) water leach through the treated sediments in the cooling pond?"

Work on the cooling pond began in November when construction crews pumped out the water that had been used to chill the hot steel from Sysco. The water had collected flakes of the molten metal. A cement-like compound was then mixed into the leftover sludge to harden it and keep contaminants from leaching out.

Work finished this spring after a cap of dirt and topsoil was placed on top of the hardened cooling pond. The project cost about $4.6 million.

Sunken areas have been taped off on mound of grassy soil for at least three weeks. The actual sunken portions are one the edges of the cap, not on top of the cooling pond itself. The backfill used as part of the cap has likely begun to settle in places, Ms. Collier MacDonald said. She said that ice underneath the soil may have melted since the project was completed.

Ms. Collier MacDonald could not say for sure why settling could not happen on top of the actual cooling pond. "First, we have to find what the source (of the problem) is," she said. "once we know the source, (then) we'll know whether or not it could happen in other places."

But the sinking on the outside of the cap should not affect the cooling pond itself, she said.

"I don't know how she'd be able to determine that now (without an investigation)," Ms. Kane said.

The agency will not be looking into the source of the settling for a few weeks. Rainy weather had made it very hard for vehicles to drive around the site, Ms. Collier MacDonald said.

(lfraser@herald.ca)