In June 2012, the tragic collapse of the Algo Centre Mall in Elliot Lake Ontario claimed the lives of two women. How did this happen? After much finger pointing, much of the blame is ultimately pointing to the concrete waterproofing supplier.
When the mall was beginning construction in 1979, Harry S. Peterson Co. was a membrane waterproofing supplier trying out a new, cheaper method for waterproofing concrete. Basically, the “Peterson system” involved using a composite sealant and polyurethane membrane only at critical joints in the concrete, rather than applying a membrane across the entire surface. Used in only one other project, this method was not only unproven, it was not compatible with the hollow precast slabs that it would be waterproofing.
The membrane was applied during the hot and humid Ontario summer, which was a major problem for the integrity of the waterproofing sealant materials. This immediately led to serious leakage problems, with water pouring into stores below the parking deck. Adding to this initial failure, the traffic flow was much higher than expected, with snow plows and traffic using the garage as a “street shortcut” to avoid backups at a nearby light.
This unaccounted for traffic caused substantial strain on the structure, leading to more unprotected entrances in the concrete through hairline cracks. The salt used on the icy roads typical to the harsh Ontario winters caused corrosion to the steel substructure within the concrete, ultimately leading to the catastrophic failure of a critical weld.
The most tragic part of this situation is that it could easily have been prevented. Cutting corners on costs for something as important as protecting the core of a massive structure doesn’t make sense. By implementing long-term waterproofing solutions to key areas, infrastructure can remain safe for decades.
Several studies indicate that politicians, planners and specifiers need to be forward thinking and willing to implement long-term strategies which will save millions of dollars in repair costs down the road.