Static pipe bursting
continues to establish itself as a preferred method of pipe rehabilitation
and replacement in the United States and North America. Literally
hundreds of thousands of feet of pipe has been replaced throughout
the US in just the last few years utilizing this trenchless method.
Allen Steele Company, Lake Delton, WI is a good example of an
established contractor expanding its service offerings to include
static pipe bursting. Recently, the contractor took on one of
the largest pipe bursting projects ever completed in the middle
of the country’s heartland, Wisconsin.
To burst and
replace the over 20,000 lineal feet of 4-inch force sewer
main the Allen Steele Company choose the Grundoburst
800G static pipe bursting system from trenchless equipment
manufacturer TT Technologies, Aurora, Ill.
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The project in Wisconsin was performed for the Ho-Chunk Nation
and the Rainbow Casino. The casino is located in the town of Port
Edwards about 5 miles southwest of the city of Nekoosa. According
to Scott Chilson, Project Engineer, MSA Professional Services,
Baraboo, WI, project planning and preliminary design began in 2003.
The project included replacing approximately 24,000 lineal feet
of 4-inch HDPE sewer force main with 8-inch HDPE. The design was
completed during 2005-2006 and the project was bid in early summer
of 2006.
Chilson said, “The
project was bid by invitation only and the Allen Steele Company
was the successful bidder. The firm has been performing HDD construction
services for several years. However, this was the first pipe
bursting project they have performed. MSA and Ho-Chunk contacted
Bill Brennan, TT Technologies, for assistance using the trenchless
static pipe bursting method.”
For the project, the Allen Steele Company utilized a Grundoburst
800 G static pipe bursting system from trenchless equipment manufacturer
TT Technologies, Aurora, Ill.
The Allen Steele Company was founded in 1957. Since that time,
Allen Steele and his company have earned an excellent reputation
with owners and engineers as a premier underground and site utility
contractor. The company specializes in excavating, site grade,
municipal and commercial sewer and water, as well as underground
cable installation services.
MSA Professional Services was founded in 1962. The company boasts
a wide range of engineering, architectural and planning services
for the municipal and government, transportation, real estate and
development, and environmental sectors. Headquartered in Baraboo,
Wisconsin, the company has twelve satellite offices in four states
and has garnered a solid reputation for quality and vision.
Together MSA Professional Services and the Allen Steele Company
completed one of the largest static bursting projects in the Upper
Midwest.
Crews utilized a specially designed quad cutter to split the
existing 4-inch HDPE force main. The undersized main
was replaced with 8-inch HDPE.
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According to TT Technologies pipe bursting
specialist Bill Brennan, static pipe bursting has established itself
as a dependable trenchless pipe replacement method throughout the
US. He said, “While
pneumatic pipe bursting continues to be a favorite pipe bursting
option, static pipe bursting has really become an attractive
pipe replacement method. I think a lot has to do with the fact
that there is a lot of static pipe bursting experience out there
now. That may not have been the case 10 years ago, but now engineers
and contractors are being exposed to the process all the time.
And even new contractors can enter into projects with confidence
because of collective static bursting experience that’s
out there. The Allen Steele Company is a prime example of that
taking on 20,000 feet their first time out with static bursting
equipment. They’re also a highly skilled group.”
The static bursting process is simple, yet effective. 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, typically HDPE.
Patented 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 operation.
And while HDPE is commonly used, new techniques and technologies
are allowing contractors a choice when it comes to product pipe.
Other pipe materials that can be installed through static bursting
include ductile iron, PVC, specially designed clay and even steel.”
According to Brennan
recently there has been great success in utilizing other product
pipe materials with the static bursting process. He said, “In many cases HDPE is the right choice
for product pipe. However, in some situations it’s ductile
iron, in another it’s PVC. Over the last several years, techniques
have been developed to allow the use of a variety of product pipe
options, like ductile iron and PVC, with static bursting. It provides
contractors, engineers and municipalities a great deal of choice
and flexibility when it comes to the Grundoburst static bursting
method and further demonstrates the maturity of the process in
the US market.”
To speed the bursting process crews would divide a 1,000-foot
section of pipe into two bursting runs. By placing the
Grundoburst unit in the middle of the two runs, crews were
able to burst one section of pipe and feed the Quicklock rods
into the next bursting run simultaneously. So as one
run was completed, crews simply rotated the bursting 180 degrees
to burst from the other direction.
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According to MSA, the Rainbow Casino and nearby
businesses and residences had been served by an aging sanitary
pump station and force main. The pump station and force main conveyed
the wastewater to the Nekoosa Wastewater Treatment Plant. The city
accepts the flows from the casino and other users. Growing concerns
with the reliability and capacity of the existing pump station
along with pending future expansion and development prompted
the Ho-Chunk to consider action.
Chilson said, “MSA
Professional Services evaluated the existing system and offered
a recommendation. The outcome of the evaluation was to replace
the pump station with a new facility and to increase the size
and capacity of the existing force main. A site for the new pump
station was readily available. However, the privately owned force
main was located in the public right-of-way controlled by Wood
County, the town of Port Edwards, and the city of Nekoosa.
During the preliminary
design, MSA and Ho-Chunk contacted the county, town, and city
to discuss the feasibility of the installation of another larger
force main. The governing agencies granted the Ho-Chunk permission
to install and operate in the public right-of-way. However, they
expressed a desire that the construction be conducted in the
method that would minimize surface disturbance.”
Based on that request,
static pipe bursting became the method of choice for the project.
According to Steele, the previous main installation project left
a poor impression on the residents of the area. He said, “When the original 4-inch force main was
installed, the contractor did not restore the roads, driveways
and turf to the local resident’s satisfaction. MSA Professional
Services considered the options of open cutting, directional boring
and pipe bursting. Open cut was ruled out because of the public
relations situation. MSA Professional Services and TT Technologies
worked together to come up with the best approach to this project.” The
final project design included approximately 20,000 lineal feet
of static bursting and another 4,000 feet of HDD installation.
Because of the significant upsize and sandy soil conditions, Bentonite
lubrication was used. The Allen Steele crew utilized a Grundomudd
DS 500 Bentonite mixing and delivery system, also from TT Technologies.
During bursting runs a Bentonite slurry was pumped through a
hose that ran inside of the new 8-inch HDPE. A hole was drilled
near the lead end of the pipe and a Bentonite manifold was attached.
This allowed the Bentonite slurry to be pumped during bursting
operations.
In addition to running
Bentonite during operations, a specially designed splitting head
was used to split the existing HDPE. Brennan explained, “For
this situation, we used a quad cutter instead of a standard bursting
head to split the existing HDPE. Because the existing PE pipe
was relatively new, the splitter was the best option.”
Bentonite
lubrication was used because of the significant upsize
and the sandy soil conditions in the area. A special
Bentonite manifold was installed on the lead end of the
pipe to delivery the lubricant.
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According to Steele,
for a typical run, the crew would choose a 1,000-ft section of
pipe and divide it in half, placing the exit pit in the middle
of the run and dig launch pits at either end of the 1,000-ft
section. He said, “We
used a 5-foot spreader bar on a 25-foot box for the exit pit,
where the hydraulic bursting unit was placed. For the launch
pits we were able to get by with an even smaller, 8- by 20-ft
box. The existing 4-inch main ran between 6 and 7 feet deep in
most areas.”
This approach helped speed up the bursting process and improve
efficiency. First crews would feed the Quicklock bursting rods
through the first 500-foot section of pipe from the exit pit to
the launch pit. After the rods arrived at the launch pit, the splitting
head, expander and fused HDPE were attached and pullback begins.
At this point, instead of removing the bursting rods one at a
time at the exit pit during the pullback, they pass through the
hydraulic bursting unit, connected, and are fed into the next 500-ft
section of pipe. So as one run is completed, the rods are placed
in the next section of pipe. All the crew needs to do is lift and
turn the bursting unit 180 degrees and prepare for the next run.
Allen said, “The
fusing of the pipe took place well prior to the actual bursting.
Installing the trench box and maintaining the safety for the
crew was probably the most time consuming aspect of the project.
The actual pulling operation took between two and three hours
per 500 feet. Plus, we were able to pull 500 plus [feet] per
pull and we were able to make two pulls from each pit, which
really helped speed things up. The crews had one week in particular,
working nine-hour days, where they were doing 1,000 to 1,100
feet per day. During that one week period of time the boys put
in over 6,000 feet of new pipe.”
Chilson said the project was challenging in numerous ways. He said, “The
project was big in length at just under five miles. It also included
a large upsize, increasing the force main two diametric sizes.
We had to contend with a short construction schedule, plus coordinate
and gain the trust of a new construction method by all the project
stakeholders. The project itself was basically the construction
of a private utility within a public right-of-way that crossed
three separate jurisdictions. Physically, the main crossed a trout
stream, two high-pressure crude oil pipelines, two county highways
and a highly traveled county road. There was even a fiber optic
communication line located above the existing force main. This
project had a little bit of everything.”
According to Steele
for a first bursting project this one left a positive impression
on his crews. He said, “By the end
of the project, the crews enjoyed it [the bursting process]. They
got the system down pat. In the beginning they resisted. The crews
were accustomed to open cut techniques. They’re very good
at it. But now, we can see the benefits of static pipe bursting.
We’ve done a 180 on it. In the right place, it’s the
right way to go.”
Chilson said, “From the engineer’s
perspective, the large number of stakeholders plus the numerous
physical challenges related to this project style added to the
long list of unknowns and risks. In the end though, the project
was completed on schedule without any unforeseen situations.
The project team, including the Allen Steele Company, TT Technologies,
and MSA Professional Services, made this happen. The success
of the project was due to a true team effort. The project would
not have been possible without the trust the Ho-Chunk Nation
extended to MSA in allowing the use of this progressive construction
method and approach.”
Jim Schill
Technical Writer
Mankato, MN
Underground Construction,
February 2007
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