a function of the wind speed and the number of sheet
pile pairs.
“We welded 70-foot to 80-foot sheets that were around
25 feet tall, to make sure that the two pipe piles would
have enough embedment into the ground to resist the
shear forces and bending movements transferred to the
pipe piles as a result of the wind forces,” he said.
Describing the robust nature of the frame, Alves says
the structure was comprised of steel beams welded to two
25-feet-tall steel pipes.
“The bolt connections were required to ‘split’ the
frame so we could transport it to the site,” he said, stating
that the installation procedure was as follows:
• Prepare a stable working platform before sheet
pile installation.
• Install two pipe piles (30-inch OD with 3/8-inch-thick
wall); horizontal spacing between the two pipe piles
was approximately 48.5 feet.
• Hoist sheet pile frame onto the two pipe piles. The
frame consisted of two piles with larger diameter
pipes than the driven piles. Attached to these were
two horizontal W24×117 beams at 15- and 28-feet from
grade, respectively.
• The sheet piles were welded to the frame at the
beams’ locations (the frame could hold up to
10 sheets).
• The sheet piles were then driven into the ground.
On site, HFDI crews used their lattice crawler crane
with a 180-foot boom with an APE Model 150T vibratory
driver. A Gardner Denver ADT 3800 air track
drill, supplied by Southwest Contractors was also
used. The AZ19-700 and PCZ26 sheet piles were supplied
by Samuel Roll Form Group through Titan Tube
and Metal.
Alves says on-site testing was all part of the process.
For example, the shoring system was designed, installed
and maintained to prevent detrimental settlement and
lateral movement of existing facilities, adjacent properties
and completed works.
“Inclinometers, survey targets and tiltmeters were
installed by the general contractor to monitor movement
and settlement. Geophones were also used for vibration
monitoring,” he said.
Several environmental sustainability measures were
placed as well.
“The greatest benefit to the environment was the
installation of the water cut-off system. The reduction
of water ingress into the construction site allows a more
manageable and sustainable use of aquifers and reduces
the migration of contaminants that can be initiated or
exacerbated by extraction/diversion,” Alves said, concluding
that the project is a major step in moving water
treatment forward in B.C.’s Lower Mainland.
PROJECT SPOTLIGHT
HFDI engineered frame holding the sheets in place during installation
26 Issue 4 2021 www.pilingcanada.ca
/www.pilingcanada.ca
