City administration is recommending the continued use of calcium chloride on Edmonton roadways, but one chemical engineer is sounding off against the studies that city staff say support the ongoing use of the controversial anti-icing agent.
The studies, released Thursday, looking into the city’s two-year pilot project on calcium chloride, come after many months of heated discussions surrounding the solution and its effectiveness.
Deputy City Manager Gord Cebryk said the studies provide councillors and taxpayers a “complete picture” of the effects of the snow and ice program.
“While we appreciate any operational or policy decisions will have trade-offs, we feel the benefits of our data-driven approach outweigh any of the disadvantages,” he said.
However, chemical engineer Arthur Potts has issues with the studies, citing small sample sizes, lack of raw data and the short window for evaluation.
The findings from the city-backed studies include:
- A University of Alberta study that showed vehicle collisions fell up to 20 per cent in some areas during the two-year pilot
- Comparing five samples in fall 2018 and again in spring 2019, one study by Tetra Tech found lower concentrations of road salt and calcium chloride have “limited effect” on concrete durability while high concentrations of calcium chloride will “negatively affect the long-term durability of concrete”
- Comparing select roadways pre- and post-winter, another study by Tetra Tech, found “no discernible differences in roadway surface conditions” and that while long-term exposure may result in some decrease in asphalt strength, it was not deemed significant enough to have a negative impact on performance
- One study by CorrPro found a field program evaluating metal corrosion was “inconclusive due to insufficient time in the field”
Potts said he takes issue with the University of Alberta vehicle collision study because the raw data is not included.
“If I’m a reader of this report, either as a citizen or a councillor, I want to see that raw data reflects really what the conclusions are. If not, I want to ask some more questions. I can’t even ask those questions without that raw data,” he said.
Potts also points to the study where five locations of concrete were sampled.
“With such a small sample size, you would normally not consider that statistically relevant. I’m not sure how that translates to any idea of what’s going to happen long-term.”
The city said they only used calcium chloride twice last winter; Potts said that raises questions about the conclusions in the studies, many of which only looked at one year of the pilot.
“I’m not really sure how, statistically, they got a sample size that allows them to draw the conclusions they’re stating in this report,” Potts said.
“If you’re now drawing conclusions from a very small sample size, based on one year, I wouldn’t feel comfortable with that if it were my property. I don’t think the city should be comfortable with that if it’s our property, meaning the infrastructure.
“If the motivations are to use facts to make good, sound decisions, then I’m not sure why we’re not using facts that exist already.”
Watch below (Jan. 14, 2019): The use of calcium chloride on Edmonton roads has been a controversial issue the last couple years. Now, a newly uncovered memo is raising more concerns. Julia Wong reports.
The use of the anti-icing agent in Edmonton has been controversial, with some residents sharing worries and concerns at committee meetings.
Global News pressed Cebryk on why administration is pushing forward with the program when there’s the possibility taxpayers do not want it.
“In moving forward with trying to achieve bare pavement and improve safety, what we are doing is presenting data that will support that decision,” he said.
“As outlined in the report, we’re trying to focus on safety and there are trade-offs for any type of application, whether that be sand, salt, brine.”
The report into the pilot program comes eight months after Global News revealed a then-previously undisclosed city memo citing that calcium chloride was 20 per cent more detrimental to concrete than road salt, or sodium chloride, and created 12 per cent deeper ruts in asphalt compared to road salt.
The findings in the city-based studies do not align with the city memo.
“In that memo, that referenced one particular lab test and that lab test also identified that further in-field studies would need to be undertaken to confirm the actual results,” Cebryk said when asked to reconcile the differences.
Cebryk said he does not expect any budget impacts related to infrastructure wear-and-tear if the calcium chloride program continues.
He said, if anything changes, administration will approach city council for additional taxpayer funding.
The issue goes to committee on Sept. 4.