PROJECT SPOTLIGHT
Rogers Centre) to raise the grade across much of the
project area by an average of two metres.
“This is of one of the largest waterfront revitalization
projects in the world and certainly one of the most ambitious
and significant infrastructure projects in Toronto’s
history,” said Toronto Mayor John Tory at the groundbreaking
ceremony. “The project will unlock the potential
of underutilized waterfront lands, protect the area from
flooding and create new parks, natural areas and neighbourhoods
where people will live, work and play.”
PLFPEI will completely transform approximately 290
hectares (715 acres) of underdeveloped industrial zone
into a new and vibrant – and resilient – downtown neighbourhood
called Villiers Island. The economic importance
of this development cannot be overstated. A third-party
economic impact study conducted by urbanMetrics in
2016 estimated that the project will generate approximately
51,900 full-time years of employment, $5.1 billion
in value added to the Canadian economy and $1.9 billion
in revenues to the three orders of government.
The project will also provide critical flood protection
by creating a naturalized mouth for the Don River,
which will be surrounded by new parks, green spaces
and public amenities, in addition to new wetlands to
support native species better.
“Toronto’s waterfront is the gateway to the city and
its Port Lands area has bountiful potential, but it has
been underutilized for decades,” said Richard Males,
field technician at Keller North America. “The new
Don River channel will allow flood waters to flow safely
into Lake Ontario, concurrently providing habitats for
wildlife, residential development and a new community
oasis close to the heart of the city.”
The local branch of Keller North America operating
out of Acton, Ont., along with support from Keller’s specialty
services division, came onto PLFPEI in December
2020, and recently completed Phase 1 of the project
using its diaphragm wall technology. Diaphragm walls
are installed as a series of panels (or trenches) excavated
to specified depths and widths while being supported by
an engineered bentonite slurry. A rebar cage is installed
and the excavation is filled with concrete to form a reinforced
panel.
Diaphragm walls were selected over secant piles
because of the significant advantages the technology
brings, including fewer construction joints, a stiffer wall
with less overall deflection and substantial schedule and
financial benefits for the client.
“The diaphragm wall was designed to act as a temporary
bulkhead and support of the excavation system
to allow for the excavation of the new west mouth of
the Don River into Lake Ontario,” said Males. “It is also
acting as a permanent water cut-off for the new river
channel to prevent contamination migration from existing
soils. This innovative solution offered a reduction in
the overall construction schedule and exceptional cost
savings for Waterfront Toronto.”
Using its Bauer BC 40 Hydromill hydraulic cutter,
Keller installed the elements of the diaphragm wall with
a 25- to 30-centimetre overlap to meet excavation verticality
tolerances, as well as to ensure high quality joints
between the panels and to comply with the project’s
water tightness requirements.
“The BC 40 Hydromill has hydraulic cutter wheels,
which can excavate through an array of soil conditions
– including hard rock – and is supported by a large crane
(Liebherr HS885 HD hydraulic crawler crane), which
handles the weight and supply of hydraulic power to
the Hydromill,” said Males. “The BC 40 Hydromill was
the workhorse of our operations and performed phenomenally
through the sand, silts, soft clay and shale
bedrock where the machine’s output is among the best
in the industry.”
The diaphragm wall at Port Lands was constructed
using two different panel designs: primary and closure
panels. The Keller team first excavated ‘Primary Panels’
in a process requiring three ‘bites’ to complete. The first
bite on one side of the trench, the second on the opposing
side and a third completing the excavation in the middle;
repeating until the desired depth was reached. The length
The Port Lands’ worksite
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