Edmonton city councillors are demanding to know why a key composting facility in Edmonton had such structural damage that it had to close suddenly, forcing food waste to be sent to the landfill for the winter.

Engineers discovered structural problems with the roof of the aeration hall in the composting facility, creating safety problems for staff working at the 270,000-square-foot building.

"The roof can't hold a live snow load, that's why we made the decision to suspend processing organics in the processing facility," said Mike Labrecque, branch manager of waste services.

"What happens next? It's too early to speculate," he said, adding it's also too early to say how much it would cost to fix the facility.

Coun. Michael Walters wants to know why a previous assessment didn't detect problems sooner at the composting facility. (CBC) However, a report in front of the city utility committee Tuesday says the financial implications may "potentially be significant."

Michael Walters is one of several councillors wondering why past inspections didn't reveal the problems sooner.

"The project-management and asset-management challenges we've had in the last number of years are no secret," he said.

"How this asset turned from being in good condition to being in very poor condition very quickly — we're still waiting to understand."

Labrecque said the waste services department is looking at other options for composting, such as other locations in or around the Edmonton area.

"It's a massive facility — we handle 150,000 tonnes of material every year."

Waste services staff are being asked to report back to council with a detailed plan on how to fix the composting facility or possibly demolish it. There will also be a review of the previous assessments.

Those reports are due Feb. 23.

In the meantime, all food waste in Edmonton is being sent to the landfill.

Composting organics comprises 16 per cent of the materials diverted from the landfill.