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Water is a highly valued commodity in Utah. The state is second
only to Nevada for the dubious honor of the least amount of annual
rainfall at a meager 13 inches of precipitation per year. Irrigation
and water management has been an essential part of life in this
section of North America for hundreds of years. Simple irrigation
canals have been discovered in this area that date back to prehistoric
times, well before the discovery of the “ New World
.” While the practice of water management has advanced with technology,
the concepts behind it remain very much the same: conserve and manage the water
supply while serving the people, agriculture and industry.
That management includes providing and maintaining
the proper infrastructure to handle the job. That also means replacing
it when it becomes old, deteriorated or outdated. That was the
situation recently in Ogden, UT.
The CNC crews utilized the Grundoburst static pipebursting
system that allowed them to use a restrained joint PVC
product pipe. The Certa-Lok Yelomine PVC pipe assembled
easily as the bursting operation proceeds, without the
need for special fusion equipment.
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The Weber, Box Elder Conservation District
is the irrigation water supplier for Ogden City residents. Most
of the district’s
existing infrastructure consists of steel main lines, many over
50 years old that are in need of replacement. According to Claude
H. Nix Construction/Jasco, Inc. Pipe Bursting Division Manager
Jay Garrett, replacing those lines is not always easy. He said, “Often
those mains run through areas that make replacement very difficult.
The line that was replaced in this project was an 8-inch line running
through a narrow park strip. The line was over 60 years old and
less than 5 feet deep. Our job was to replace the 8-inch steel
with a new 8-inch PVC line. The Weber, Box Elder Conservation District
accepted our bid to replace this line using pipe bursting to see
how it would perform in a tight, landscaped area.”
Garrett turned to pipe bursting specialist Jim Moore from trenchless
equipment manufacturer TT Technologies,
Aurora, Ill for technical
support. He said, “There were important aspects to this project,
one of which was the choice of product pipe. This was the first
pipe bursting project that utilized CertainTeed Certa-Lok™ restrained-joint
PVC. It is significant step for pipe bursting and for the product
pipe industry. It expands the capabilities of both products and
gives municipalities and project owners another level of choice
when it comes to replacing deteriorated infrastructure.”
A Grundoburst 400G static pipe bursting system from TT Technologies
was chosen to burst and replace the existing steel irrigation mains.
Contractor Background
Over the past 30 years, Claude H. Nix Construction/Jasco,
Inc. (CNC) has grown as the leader in providing solutions to difficult
piping projects in Utah, Southern Idaho, and Southwestern Wyoming
.
CNC President Stephanie Nix said, “We
focus on investigating new technology and using the best so we
have the right tool for the job. We provide our customers with
fair and complete bids, and work independently and professionally
once we are on the job. We are in business to provide our customers
with quality installation of underground water, sewer and storm
drain pipelines using the best construction technology and knowledge
available.”
The Pipe
The
Groundoburst's specially designed bladed rollers makes
bursting difficult host pipe like ductile iron and steel
possible. In this case, CNC crews replaced 1,300 lf of
8-inch steel irrigation main with the static system.
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According to Moore, product pipe material
selection can sometimes be a volatile subject. He said, “It
has been a stumbling block. Many utilities are so invested in certain
pipe materials that it is almost impossible for them to consider
other piping materials. While there is a high level of familiarity
with the application of HDPE pipe in pipe bursting, there is still
considerable interest in other pipe materials by owners, engineers
and contractors.
Pipe manufacturers, like CertainTeed,
are working diligently with pipe bursting equipment developers
and manufacturers to find real world ways to adapt their pipe
products to the rigors of pipe bursting installations. It takes
the extensive experience of these parties to find suitable ways
to install these pipes through the pipe bursting process. It
is very much a collaborative effort,
like the project in Ogden.”
Steve Gross, Director of Marketing
for CertainTeed’s Pipe
Group, believed Certa-Lok Yelomine was an excellent choice for
this pipe bursting application. He said, “Yelomine pipe is
made of modified polyvinyl chloride, which provides improved mechanical
properties, higher pressure ratings and better flow performance
than other thermoplastic materials. Plus, it will allow the district
to stick to a proven long-lasting material that works seamlessly
with existing infrastructure.” Gross also noted that Yelomine
in particular is easy for contractors to work with due to its unique
spline-locking system that eliminates the need for fusion equipment,
saving time and money, and the need to string-out hundreds of feet
of preassembled pipe, which may not fit in congested areas.
On The Job
With all of the
components of the project in place, work was ready to begin on
the irrigation pipeline. Because of the lack of rainfall, many
areas employ a dual water system as a means of conservation.
With a dual system, one system is dedicated to potable water,
while the other, separate system, carries water that is used
for irrigation, as well as commercial and industrial applications.
Moore said, “This type of secondary non-potable
water system is typical of the area. Basically residents use the
system for caring for their lawn and gardens during the summer.
It’s also used for agricultural irrigation. In the winter
the lines are drained and shut off. This particular steel line,
which was used for irrigation, was in pretty bad shape.”
Garrett said, “There were over
63 point repairs in the 1000 feet that was to be replaced. The
preparation was time consuming due to the number of service connections
to the homes in the area. Most were put in after the irrigation
line and some were in direct contact with the old pipe. There
were 4 tees that needed to be cut into the new line, so a pit
was set up at these each of these locations. Approximately 1200
lineal feet of the 1300 total lineal feet was installed using
pipe bursting. Two road crossings were constructed by directional
drilling and 60 lineal feet was installed open cut.”
CNC crews divided the 1200-lf project into four bursting runs.
Not only did crews contend with tight working conditions, but traffic
was also a concern because of an elementary school a few blocks
away from the work site. Because these irrigation lines are drained
and shut off in the winter to prevent freezing, the lines are set
only a few feet below the surface. Launch and exit pits were typically
4 feet wide by 10 feet long by 3 1/2 feet deep.
According to Garrett, crews also saved
space by utilizing the PVC pipe. She said, “We used Yelomine Restrained Joint PVC
pipe which meant that we didn’t have to contend with 450
feet of fused pipe crossing driveways and streets while we were
bursting. That helped with space issues. We also needed to make
sure to secure the potholes well because of the close proximity
to the school. And we paid very close attention to the adjacent
utilities.”
Quicklock bursting rods are linked together, not screwed
together, like traditional drill stems or other static
systems. This system speeds the installation process
as well as the breakdown procedure. The rods can be quickly
removed one at a time at the exit pit as bursting is
in progress.
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According to Moore, the CNC crews
handled the adversity well. He said, “Probably the biggest
challenge the CNC crew faced on the project was with other water
lines and gas lines that in certain areas were literally sitting
right on top of the steel main we were replacing. In some instances
a loop was placed on the line to provide more room for bursting
and in other cases we slowed the bursting process down and monitored
the area closely to make sure we could make it through. This
is a huge advantage to the static bursting process, the ability
to manage your speed.”
Once the launch and exit pits were
established and the adjacent utilities and services potholed,
the Grundoburst hydraulic pulling unit was placed in the exit
pit. The crew then rodded the existing line with the Grundoburst’s
Quicklock bursting rods. Once at the launch pit , the roller
cutting blades, bursting head, expander and first section of
PVC were attached, and pullback was ready to begin.
Moore said the bladed rollers are key
to pipe bursting steel. He said, “During the static bursting
process, specially designed bladed rollers are pulled through
an existing line by a hydraulically powered bursting unit. As
the bladed rollers are pulled through, they split the host pipe.
An expander attached to the rollers forces the fragmented pipe
into the surrounding soil while simultaneously pulling in the
new pipe.
The bladed roller configuration is
an essential part of the Grundoburst’s
success. The specially designed bladed rollers actually split the
host pipe instead of ripping or tearing it. This is a clean process
and prevents potential damage to the product pipe.”
Average bursting times for the CNC crew ranged between an hour
and an hour and a half per 300- to 400-ft runs. After a bursting
run was completed, crews would set to work tying back in the services
to the new PVC main and restoring the launch and exit pits.
Everyone involved considered the project
a great success. Moore said, “There were several challenges
on this project and several successes. It was very difficult
to get around those tight utilities. But it was exciting to be
able to use a new product pipe in the restrained joint PVC. In
the end it was great job all the way around by the Nix Construction
crew.”
Underground Construction, July 2006
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