As the only Saskatchewan company capable of extensive high capacity structural remediation, Innovative Piling Solutions used its expertise to salvage a condo building that was sinking fast
Fortunately, complete engineering failures are rare in the construction world.
But when they do happen, the best remediation plans often call for an innovative approach that identifies how to fix structural problems as efficiently and cost effectively as possible.
Such was the case with the Windermere Condo in Prince Albert, Sask. The five-storey, 25,000-square-foot residential building was originally tendered in the fall of 2012 and construction began shortly thereafter. The building was 99.5 per cent complete and residents were ready to move in about two years later.
That’s when Innovative Piling Solutions (IPS) of Martensville, Sask. – which had unsuccessfully bid on the original job – was contacted about fixing a serious problem. The building was sinking.
“The west end of the building had sunk about nine inches and there was differential settlement all across the building,” said Banain Cote, vice president of operations at IPS. “The middle had sunk six inches and the east end had sunk three.
“We were contacted by Rempel Engineering out of Saskatoon, who was informed of the problem by the receiver of the then-bankrupt original contractor. The condo was unsellable because it was sinking and the receiver wanted it fixed, of course.”
Cote says it was clear that the structure was an engineering failure of catastrophic proportions.
IPS began remediation work in the spring of 2015.
“We went in and completely disregarded the original geotechnical information. We brought in P. Machibroda Engineering and they went in and did a new geotechnical survey with CPTu testing to get more information about the soil, so we could figure out exactly what was happening under the building.”
As it turned out, the original piling contactor had terminated the piles in a soft sand layer, with under-sized and under-length piles which were incapable of supporting the building’s weight, even in optimal iterations.
IPS had to get creative to figure out just how bad the problem really was.
“We installed two piles in the parking garage [which had seven feet of head room] and performed load tests on them,” said Cote. “We used the building itself to resist the testing forces on the piles. We had some pretty interesting load tests. We kind of pioneered what we called ‘dead weight load tests’ using the static weight of the building, measuring lateral and vertical deflection on the pile, and vertical deflection on the building itself.”
The load testing revealed that the Windermere Condo was severely under-supported, with some areas revealing just 20 per cent of what was really required.
“It was very, very bad engineering by the previous piling contractor,” said Cote. “Some of these columns that were built only had one pile under them, and we had to go in and put five larger piles under the caps to support them. One section of 50-foot-long basement wall had no piles under it at all.”
To salvage the building, IPS installed a total of 227 screw piles: 200 in the parking garage and 27 around the outside perimeter. The majority of the interior piles had to be sectioned in, so they were installed in five- or six-foot pieces. Then, the piles were bridged with a steel beam under the existing wall to properly support the entire structure.
Cote says installing the outside piles was straightforward, although the interior work in the confined parking garage presented a real challenge.
“There was only about seven feet of headroom in the underground parking garage. Nobody could have gotten equipment in there to do the work. But the floor was not levelled properly anyway, so we suggested taking it out and removing two additional feet of dirt as well to give nine feet of headroom.”
That work, performed by Ruszkowski Enterprises, allowed IPS to bring in its Bobcat T650 for the interior piles and its Bobcat S630 skid-steer loader for materials handling. Outside, a Hitachi 270 excavator was used for the large piles.
As the job progressed, IPS discovered what would prove to be its biggest hurdle. The condo’s mechanical room had grave structural problems as well, with a wall unable to support itself. It looked like an entire basement wall would need to be removed to provide access to shore up the wall of the mechanical room.
To do this work, all the glycol and other fluids from the mechanical room would have to be drained, which would cost about $400,000 over a period of five weeks.
“So we said, we can just fit in there,” said Cote. “We will cut out a section of the wall and shore it up. We got in and out and saved them that money and time.”
IPS had clearance of just 65 inches to get into the mechanical room. In some places, Cote says hanging ducting allowed only four feet of headroom.
But, as its name implies, IPS specializes in innovative solutions to get a job done right, often saving clients both time and money.
As another example, halfway through the Windermere job, IPS contacted the owner and changed the terms from a stipulated price to a time and materials price, which ended up saving 2.5 per cent on the total fee.
IPS wrapped up the work in five weeks with assistance from Miller Contracting, which handled much of the interior concrete work.
The Windermere Condo building officially opened in the summer of 2016, and is currently being used by Saskatchewan Polytechnic for student housing.
Cote says the project is a good reminder of the old adage that you get what you pay for.
“We can’t stress that enough to clients,” he said. “Screw piles have become more readily available and unknown contractors are taking on jobs they shouldn’t, or existing contractors are trying to cut corners. We have never subscribed to that; I would rather be more expensive but do it right.
“This is a perfect example. There was no excuse for what happened to that foundation.”
Regardless, the Windermere Condo job certainly highlights the innovative spirit at the heart of IPS.
“We’re not a box piling company,” said Cote. “This project was a real challenge, installing high capacity piles in a very small area. If you ever want to know how to build a condo after it’s already standing, this is how.” 