ELLIOT LAKE, Ont. -- The inability to stop severe leaking at the doomed Algo Centre Mall was a disheartening mystery for years but was likely the result of a basic design problem, an inquiry heard Friday.
In a second day of testimony, the man whose company tried to waterproof the roof-top parking deck testified he now believes the designers failed to take into account the heavy traffic -- including buses and snow plows -- that would use the exposed garage.
"The primary source of our problems was the choice of the hollow-core structural deck and the way it was constructed," Dave Monroe testified.
"There were too many slabs of hollow-core precast concrete loosely tied together and they moved more than we would have expected and in ways we didn't expect."
Monroe, former vice-president of Michigan-based Harry S. Peterson Co., said the leaking from the parking deck into the stores below was more trouble than the company had experienced.
"We realized we had problems we did not understand," Monroe said. "It was very disheartening."
He described a series of remedial measures -- some after a controlled flooding of the parking deck -- including replacing seals and caulking.
At one point, he said, they thought they had fixed the problem that began after construction ended in 1980.
"We felt like, 'Eureka!' " he said.
The euphoria didn't last, with serious leaks re-emerging within a few weeks.
"The mystery continued."
It would be a decade later -- in 1992 -- that an engineering-inspection report stated: "The design used for this roof slab is inappropriate in achieving a water-tight condition."
Yet even a seemingly simple solution, such as restricting access to the garage, was never properly implemented and there were no other parking options for shoppers, the inquiry heard.
After years of water and salt penetration, the rooftop garage collapsed June 23, 2012, killing two women and injuring several others in the mall below.
Monroe said he never imagined the roof deck would create a safety hazard. "When I heard (about the collapse) I was shocked. I was very sad."
Lawyer Douglas Elliott, who represents citizens of Elliot Lake, praised Monroe for his admission that his company's waterproofing system failed.
"I don't want you to think your company was the only one who made mistakes," said Elliott, who called Monroe's testimony a "healing moment" for the community. "The people of Elliot Lake are good people and I know they will find it in their hearts to forgive you."
The inquiry is looking into the reasons for the collapse and the emergency response to the disaster.
-- The Canadian Press