Sears and Suncor have been found jointly responsible for a decades-old gasoline leak near North Hill Mall that still needs cleaning up.

The spill came from underground gas storage tanks that had been leaking for years in the 1970s and early 1980s under a gas station owned by Sears — which went out of business in 2017.

A plume had developed over the years, gradually expanding off the original site and seeping under a nearby neighbourhood. It is present in much of the groundwater under Hounsfield Heights/Briar Hill, just south of North Hill Mall.

Gilbert Van Nes, a lawyer with Alberta's Environmental Appeals Board, says the plume affects about 36 homes in a six-block radius. He told the Calgary Eyeopener that although the leak was discovered in 1989, clean-up is not a simple task.

"It's very difficult to clean up a spill like this that's been going on for such a long period of time. In this case, it's gone underneath the community there, the whole Hounsfield Heights community," Van Nes said. "And so it's underneath people's homes ... although fortunately it's underneath a clay layer that provides protection to these people's homes."

No immediate health concerns

Van Nes said the clay barrier has been protecting residents from fumes.

"It does need to cleaned up, but it is being monitored to make sure there are no health concerns," he said. "But at the hearing we weren't able to identify any immediate health concerns to the residents there."

Recently, Alberta's Environmental Appeals Board made a decision about how to deal with the contamination.

"What we're doing is we're trying to get the plan accelerated as best as we can," Van Nes said. "Unfortunately, it probably will still take 15 years."

Van Nes explained that the first part of the process is a vapour extraction system, which is currently working to pull vapours and liquids out of the ground to reduce contamination. The plume has been stopped by a chemical barrier.

About 36 homes in the area just south of North Hill Mall are thought to be affected by a gasoline leak from a the former Sears gas station at the mall. (Google Maps)

"There's a barrier in place at the south end of the neighborhood called plume stop, which prevents the migration further south of the contamination," he said.

"And then what's going to happen as part of this plan is they're going to finish the delineation work, and delineation is basically figuring out exactly where it is in the neighborhood and look at options for trying to accelerate the cleanup as best as possible, subject to what people are prepared to put up with in their backyards."

Van Nes said Sears and Suncor have been found responsible for the cleanup.

In an order issued Feb. 5, the Alberta Environment Minister said Sears and Suncor have 18 months to determine the extent of the contamination.

Van Nes said progress on the cleanup could be affected by several variables.

"The plan right now is there's not a great deal of disturbance as planned. If people are agreeable, there's options like aerating the soil — like drilling holes and bringing more air into the ground — which would provide oxygen to food to break down the chemicals," Van Nes said. "They can also inject chemicals into the ground, but that's a plan that they're going to have to continue to work on for the next 10 to 15 years as people give them access to the property or not.

"If people aren't prepared to provide access to the property to do things like that, there's not much that Sears and the remnants of Sears can do."

Sears has set aside $7.7M

Paying for a long-term cleanup will not be cheap, and Sears has declared bankruptcy.

"It does complicate the matter," Van Nes said. "What the board's order was, and one of the issues at the hearing, was who's responsible for the cleanup. And in this particular case the board agreed with Alberta Environment that both Sears and Suncor Energy, who operated the gas station from 1984 to 1989, are responsible for this cleanup.

"So Sears is going to set aside $7.7 million dollars in a fund to fund the cleanup work. And if there's more money required to finish off the cleanup, then Suncor is on the hook for the money after that."

A consultant will carry out the cleanup.

"Sears and Suncor have retained a consultant," Van Nes said. "The consultant is basically the one doing the work and working with the local residents to make sure the cleanup gets done under the supervision of what probably will become Suncor, after the bankruptcy of Sears is complete."

With files from the Calgary Eyeopener.