Underground Infrastructure - August 2023 - 36

Rehabilitation Technology
as we need to keep everybody up to date if something changes. " .
The largest portion of the project was nearly 7,000 feet
of 6- and 8-inch VCP to 8-inch HDPE, followed by smaller
sections of 8-, 10- and 12-inch VCP to 10-inch HDPE, and
10-inch VCP to 12-inch HDPE.
" We fused all the HDPE pipe on site, for each run, "
Finnegan commented. " There was very limited space to fuse
some days. We had to make a separate fuse on the day of the
pull, which delayed us. The city also has its own certification
process for pipe fusing that we needed to go through. "
For most of the project, the mains ranged from 6 to 10 feet
deep, with some sections as deep as 12 feet. Bursting runs averaged
350 feet with most running manhole to manhole. For
traffic control, Cratus crews took the center lane of the roadway
and pushed the traffic to each side.
The pneumatic bursting system was ideal for this project.
" The straight barrel tool worked well bursting manhole
to manhole, " Mallakis pointed out. " Straight barrel bursting
tools, like the 7-inch diameter PCG 180, use a front expander.
" This is a different configuration than your standard rear
expander system. The front expander adds versatility to this
style of tool; when entering manholes you do not want to remove
and replace. The straight barrel tools can be reversed
automatically with a lever located on the in-line lubricator.
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" So, once you complete a bursting run and enter the manhole,
the winch cable can be detached from the tool and be reversed out
through the newly installed pipe. This is extremely helpful when
bursting into a manhole from a pit. Removing the tool through
the manhole is usually not possible because of space limitations
but reversing it out to the launch pit solves that problem. "
For pneumatic pipe bursting, the bursting tool is guided
through the existing pipe with a constant-tension, variable-speed
winch.
" The winch is specifically designed for pipe-bursting and
other underground construction applications, " Mallakis explained.
" The constant-tension, variable-speed aspect allows
the winch to adjust for conditions that affect line speed during
the pipe bursting operations, providing for constant and consistent
pulling force.
" Cratus also has one of our specially designed reversible
booms on this project, which creates more space to detach the
tool from the winch cable and back itself out, " Mallakis added.
" The Cratus crews were very efficient and productive. "
Navigating around utilities
While the bursting runs went smoothly on the Palo Alto project,
getting to the point where bursting could begin proved
challenging and contributed to some long days on the work site.
UI-Conference.com
Cratus crews used a special reversible boom (pictured) for the pneumatic
pipe-bursting portion of the project. The boom creates additional space
for detaching the busting tool from the winch cable in the manhole.
36 AUGUST 2023 | UndergroundInfrastructure.com
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Underground Infrastructure - August 2023

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