Underground Construction - October 2017 - 54

REHABTECHNOLOGY

Bursting In Grand Prairie
By Jeff Griffin Senior Editor

With much of the world's water
and sanitary sewer infrastructure
in the ground for more than 100
years, trenchless technologies in
many situations are the only practical or, in some cases, possible
solution.
Of those, pipe bursting offers
several benefits.
Using the old pipe as a "path," a
winch pulls a bursting tool through
the existing pipe, breaking or busting it in the process and simultaneously pulling in a new pipe behind
the tool, eliminating most excavation. Ductile slitters are available
to replace non-fracturable pipes,
such as ductile iron and steel. Frequently, pipe bursting allows upsizing of the pipe being replaced.
An example is a recent project in
Grand Prairie, TX, to replace a segment of the city's CWSRF Waste
Water Rehabilitation Project. Contractor No-DigTec installed 550
feet of 18-inch diameter HDPE
pipe at a depth of 15 feet through
Turner Park, a community sports
area.

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"Pipe bursting allowed the pipe
to be installed without tearing up
the parkland or streets running
through it," said John Newell,
president of No-DigTec. "The entry
pit was next to the road. We went
under the street, and the path of
the pipe followed a creek and also
passed under a storm drain."

Basic bursting
There are two basic methods of
pipe bursting: static and pneumatic.
Newell said that for this project,
pneumatic bursting was used. This
method employs a bursting tool
with percussion hammer action
to help the expander head break
the host pipe. A winch located at
ground level maintains constant
tension on the bursting head with
heavy metal cable.
"There was some concrete encasement under the creek and
storm drain that we had to hammer through before we got to a
sharp bend radius that followed
the creek," Newell said.

Pipe was laid and fused along
the road.
"There was plenty of space for
a good job-site layout," he noted.
"In addition to stringing the pipe,
there was plenty of room to load
the hammer and hoses."
Two bursts were made, the
longest was 350 feet, the shortest
was 250 feet. A Hammerhead
20-ton HG20 bursting head and
24-inch expander were used on
the longest burst. For the shorter
one, a 16-inch Hammerhead tool
hammer and 18-inch IPS expander were used.
"The 20-inch hammer might be
considered unusual for the project,
but we wanted plenty of power,"
said Newell. "We wanted to get
from point A to point B without
any stall outs. After going through
the encasement there was a sharp
radius before getting to the finish
line, so we put more power on the
front end to avoid the risk of getting stuck due to pipe drag."
Power for the tools came from
Sullair 900 and 375 cfm compres-

On the job are (left) John Newell,
president of No-DigTec, and Jeff
Griffin, senior editor for Underground
Construction.

sors providing 1,275 cfm output.
Support equipment included a
New Holland backhoe, two Takeuchi excavators and a McElroy fusing machine.
Newell said the original contract
was for 2,646 feet of bursting, with
550 feet added during the course
of construction. Start to finish, the
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