GREAT CANADIAN PROJECTS
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 effi-ciently
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 prob-lem.
The building was sinking.
“The west end of the building had sunk about nine inches and there was dif-ferential
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 cata-strophic
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 geotech-nical
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 sup-porting
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-sup-ported,
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 park-ing
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
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
By Lisa Gordon
PHOTOS COURTESY OF INNOVATIVE PILING SOLUTIONS
PILING CANADA 81