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by Jim
Schill
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Within
two hours the existing 280 feet of 8-inch VCP pipe
was burst and replaced with 8-inch HDPE. Once the
PCG 180 bursting tool reached the downstream manhole,
the crew put it in reverse and backed it out through
the newly installed pipe.
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NUCA
contractor Tires ‘n Tracks, Addison, Ill was recently subcontracted
to replace an aging sewer main near a high school in Hampshire,
Ill. The project was specified as pipe bursting only. Tires
‘n Tracks, like many contractors around the country,
has added pipe bursting to its list of capabilities.
Tires ‘n Tracks has been in business since 1981. The
mutli-facetted contractor specializes in directional drilling,
fiber optics and aerial projects. According to project estimator
Dan Carlquist, pipe bursting has been a good addition to
their product offering. He said, "We’ve been
bursting now for a few years. Every project we do gives
us more experience and a competitive edge. Being able to
add another method to our list of services makes us a more
versatile company."
The project for the Village of Hampshire called for the
replacing an aging 8-inch VCP sewer main with 8-inch High
Density Polyethylene (HDPE). After reviewing the project
with Tires ‘n Tracks President Chuck Cohen, the decision
was made to utilize gave a reversible bursting technique.
Carlquist said, "The stretch of main we needed to replace
ran from the back side of Hampshire High School, under a
wooded area to a manhole that was located in the curb line
of a residential neighborhood. We had no intention of tearing
up the neighborhood and disrupting traffic. That’s
why we went with a reversible bursting tool to avoid having
to dig an exit pit in the residential area."
To replace the 280 feet of 8-inch VCP, Tires ‘n Tracks
used a pneumatic Grundocrack PCG 180 straight barrel reversible
bursting tool from associate NUCA member TT Technologies,
Aurora, Ill.
Reversible
Bursting
Standard pneumatic pipe bursting tools have been used to
replace aging infrastructure since the early 1980s. According
to TT Technologies pipe bursting specialist Ben Cocogliato,
reversible tools have been around since bursting began.
He said, "Pipe bursting was developed based on the
concepts found in piercing tools, a piston inside a casing,
propelled by compressed air. The reversible feature has
been a standard on piercing tools for over 35 years. The
same holds true for bursting tools."
Reversible tools, however, are rather specialized when
it comes to bursting. Cocogliato said, "A wide majority
of the pipe bursting done in North America is done with
high production pneumatic bursting tools equipped rear
expanders. Straight barrel reversible tools utilize a front
expander configuration. This limits their overall capability,
but does allow the tool to be placed in reverse after the
bursting run is complete and be backed out through the
new pipe. The Hampshire project is a good example of a
project well suited for using a reversible tool. Larger
diameter projects or longer runs are usually best handled
with standard high production rear expander tools."
The Project
Residents in the area of the sewer main, as well as
the high school itself experienced numerous backups
during the months preceding the project. Village
officials attempted to video the line to determine
the cause of the backups. They soon discovered
that the line had been so badly infiltrated by
tree roots, it was impossible to run a video
camera through the pipe. Carlquist said, "This was one of the things
that made the project difficult and challenging. We weren’t
sure what we were up against. We knew the major problem
was massive tree root infiltration, but we didn’t
know what else to expect."
The Tires ‘n Tracks crew began by assembling a bypass
pumping system. A manhole in the back of the school was
excavated and removed. Next, the area was shored and ultimately
served as the launch pit for bursting operations. Crews
then placed a 10-ton constant tension, dual motor, variable
speed Grundowinch 280 feet downstream at the manhole in
the curb line. The PCG 180 was fused to the new HDPE pipe
string, moved to the launch pit and connected to the winch
cable. Bursting was ready to begin.
Bursting operations proceeded without problems. Within two
hours the existing 280 feet of 8-inch VCP pipe was burst
and replaced with 8-inch HDPE. Once the PCG 180 bursting
tool reached the downstream manhole, the crew put it in
reverse and backed it out through the newly installed pipe.
The front expander was detached from the HDPE and removed
through the manhole. A new manhole was placed upstream at
the launch pit and restored. The entire project took under
three days to complete.
Cocogliato said, "The Tires ‘n Tracks crew did
an excellent job on this burst. It really serves as a model
reversible bursting project."
Carlquist said, "Everyone associated with the project
was very pleased and impressed by the speed and efficiency
of how it was completed."
NUCA, October 2003
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