A marathon debate on whether the city should use an anti-icing agent to help clear Edmonton roads this winter hit the skids on Tuesday.

At a special meeting, city council gave preliminary approval to an amendment proposed by Coun. Andrew Knack that would see the city stop using calcium chloride for the 2019-2020 winter season.

"I don't think we've done enough of the analysis," Knack said of the effects of calcium chloride brine.

Crews would instead use a combination of salt and plowing to clear streets this year.

Knack's motion also called for administration to report back by June 2020, detailing "enhancements or additional measures" on how the city can reach bare pavement without salt, calcium chloride or sand.

The final decision on the city's snow and ice policy was almost a done deal, except for a blunder and a rushed move to address it.

Coun. Tim Cartmell meant to vote in favour of Knack's motion but made a mistake and voted against it, resulting in a 7-6 defeat.

While the vote could have been clarified later in the meeting, Mayor Don Iveson immediately suggested postponing the motion to the next council meeting, and council agreed.

The motion will now be subject to final approval at the next council meeting on Oct. 8.

Iveson voted against Tuesday's motion, calling calcium chloride one tool in the city's tool box.

"I'd like to use as little of it as possible," he said. "But if it's the better tool than rock salt, because rock salt causes more corrosion ultimately, then I'd rather give our experts the choice of using the right thing at the right temperature and the right precipitation conditions."

The enhanced use of calcium chloride has been controversial since the city started using it in a pilot project in 2016.

Some argue the agent corrodes metal and concrete — rusting vehicles, garage floors and other infrastructure.

The solution used by the city does include a corrosion inhibitor aimed at preventing rusting, while sodium chloride does not, several councillors noted.

Cartmell tabled a motion at a meeting last week for the city to stop using sodium chloride. That motion was defeated.

"Salt corrodes steel and metal," Cartmell said. "Salt causes rust and we all know it. It has no inhibitor."

Gord Cebryk, deputy manager of city operations, said a "wide spectrum of tools" including calcium chloride, salt, plowing and blading is the best way to reach bare pavement.

Bare pavement creates safer driving conditions, the city said, with collisions down 20 per cent since the pilot began.

Iveson supported the administration's recommendation.

"I'm prepared to delegate that authority to expert decision makers who have chemistry and engineering backgrounds," the mayor said, "as opposed to 13 lay people who have debated this to death without coming to a clear consensus."

A mistake and another delay

This week's vote marked another delay in the lengthy debate on the use of calcium chloride.

At a meeting in early September, Coun. Sarah Hamilton proposed the city continue with the combined method of snow clearing.

On Tuesday, she expressed frustration that council continues to revisit the same debate.

"It's time for us to make a decision and to work in the best interest of the people who we serve, which is to continue with a safe snow and ice control program," Hamilton said.

@natashariebe