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R.H.
White chose pneumatic pipe bursting to replace the
over 3,100 feet of aging cast iron sewer main with
20-inch HDPE. A 14-inch Grundocrack Koloss was used
with a 24-inch rear expander.
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by Jim Schill
R.H. White, Auburn,
Mass. is a third generation family-owned construction company
celebrating over 80 years in business this year. In addition
to company sponsored special events planned throughout the
year, R.H. White recently demonstrated the quality, innovation
and capability that has brought the company to this heralded
anniversary with a major pipe bursting project in Northbridge,
Mass.
According to Project Manager Matt Gibbs, the project for
Northbridge was significant for several reasons. He said, "The bursting project really represents whats
important about R.H. White. It was a challenging project
that required skill, good planning and quality workmanship.
On the other hand, it shows the companys commitment
to growth and new technology as it was our first pipe bursting
project."
In order to replace the over 3,100 linear feet of 12-inch
cast iron main, R.H. White chose a 14-inch diameter Grundocrack
Koloss pneumatic bursting system from TT Technologies, Aurora,
Ill.
Contractor
Background
R.H. White was founded in 1923 by Ralph H. White. The
company has survived the Great Depression and numerous
recessions to become one of the largest and most accomplished
contractors in New England. Beginning in 23 as a
primarily underground contractor, R.H. White expanded into
building and mechanical construction. The building and
mechanical divisions of R.H. White allowed the company
to construct anything from a water and wastewater treatment
facilities to medical clinics.
Its the underground utilities division that is considered
the cornerstone of the company. Starting over 80 years
ago with horse driven trenching equipment, this division
has grown and expanded to make R.H. White one of the foremost
utility contractors anywhere. That skill and ability would
be put to the test for the bursting project in Northbridge.
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The
constant-tension, variable-speed, dual-caption Grundowinch
is essential to the pneumatic bursting process. The
winch guides the pneumatic tool through the host providing
consistent and constant pulling force.
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Environmental
Protection
Each year cities and towns throughout the United States
are seeing more administrative consent orders regarding
the reduction of inflow into sanitary sewer systems. This
was the situation faced by the city of Northbridge. Under
the guidelines of an administrative consent order, the city
would not be able to issue new building permits for a subdivision
project until inflow was reduced to within certain guidelines.
Replacing the 3,100 linear feet of trunk main along the
Blackstone River was the key to this happening.
However, replacing that section of main would be an extremely
difficult task. A traditional design and build project would
have taken years to develop so the city looked to R.H. White
for a solution.
Gibbs said, "Well we took a look at it and saw how
difficult it was going to be. It was 3,100 feet of 12-inch
cast iron that went through a swamp, beside a mill, by a
railroad track and along a river. Actually much of the line
ran directly underneath a historic cart path between the
Blackstone River and the Blackstone Canal. During the early
1900s, the canal was used as a shipping lane and horses
would pull barges through the canal while walking down the
path. Thats also the time that they installed the
cast iron sewer main. So there were some historic considerations
as well. We needed a construction method that could operate
within these parameters. We looked at trenchless pipe bursting."
TT Technologies pipe bursting specialist Ric Micelotta
said, "A traditional open cut project probably wouldnt
have succeeded in this setting. The working area was tight
with only 25 feet on either side of the main at places.
There were historic and environmental concerns as well.
So preserving the area was a priority. Plus the line was
undersized. Trenchless pipe bursting was a good choice
for this project because it not only keeps disruption down
to a minimum, it allows you to upsize."
Project
Stats
The project at Northbridge included bursting and replacing
3,100 feet of 12-inch cast iron sanitary sewer main with
20-inch High Density Polyethylene (HDPE). The R.H. White
crew divided the project into sections, running typically
from manhole to manhole. Certain provisions needed to be
made before actual bursting work started. Gibbs said, "This
was the main trunk line that fed the wastewater treatment
facility so we needed to run a complete bypass. We used
two 4-inch pumps to power the system. The bypass also needed
to be operational 24 hours a day, throughout the project."
Once the bypass was established, crews began bursting.
Runs varied in length from 150 feet to 650 feet. The 14-inch
diameter Koloss was equipped with a 24-inch diameter rear
expander and a friction fit guide head. According to Micelotta,
the guide head increases the tool's effectiveness when
bursting cast iron. He said, "The guide head helps
out in several ways. First, it creates additional tool
length allowing the tool to really get up inside of the
pipe and break it from the insides. Second, it helps guide
the tool through the existing pipe. And finally cast iron
has a tendency to break into shards, in front of the bursting
tool. The guide head helps protect the winch cable from
the shards of cast iron."
The bursting tool was guided through the host pipe by a
20-ton variable-speed, constant-tension dual-motor Grundowinch.
In addition, R.H. White crews ran bentonite throughout
the project to overcome difficult soil conditions that
ranged, according to Gibbs, from sandy gravel to "muck." Bursting
times varied per the length of the run. Gibbs estimates,
between set up and bursting, that crews averaged 200 feet
or more per day, until they encountered the railroad track.
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In addition to bursting, the R.H.White crew needed
to complete a 50-foot section of pipe ramming under
a railroad track. Both the bursting and ramming were
firsts for the company that celebrates 80 years in
business this summer.
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An
Added Twist
One particular section of old pipe ran underneath a
set of railroad tracks and posed a unique challenge. Gibbs
said, "The history of it goes back to the early 1900s.
There was no real easement there that was legally binding
today. When we started on the project we figured the town
of Northbridge would have to apply for a new easement underneath
the railroad tracks. Initially we suggested bursting that
section, but that idea was not accepted by the railroad.
Then we came up with the idea to ram a casing around the
existing pipe. This technique was agreed upon and fell
within the guidelines of the existing centerline easement.
We believe this solution saved everyone a year of negotiating
a new easement."
With the plan approved the R.H. White crew moved in and
set up for ramming. The crew used a 14-inch Grundoram Koloss
(the pipe ramming "brother" of the Grundocrack
Koloss pipe bursting tool) to ram the 50-foot section of
36-inch diameter steel casing under the tracks. The ram
was completed on grade, between two manholes, with perfect
pitch and alignment. Crews then set to work removing the
spoil from the casing as well as the old pipe.
According to Gibbs ramming was the perfect solution. He
said, "Ramming the casing not only satisfied the easement
issue, it satisfied other conditions of the project. There
needed to be a sleeve around the new pipe. Once the casing
was cleaned out, we were able to insert the new pipe without
any problem." The ramming was another first for R.H.
White.
Looking
Back
The Northbridge bursting project represented a major
accomplishment. According to Micelotta, R.H. Whites
performance deserves accommodation. He said, "The degree
of difficulty on this project was very high. There were
challenges everywhere. Upsizing a 12-inch line to 20 inches
is always challenging, let alone in these conditions. Add
to that the fact that this was not only R.H. Whites
first bursting project, it included their first ramming
project too, it really speaks volumes about the quality
and competence of their crews."
Gibbs said, "This was a first for the company. It was
a pretty big undertaking if you look at the fact that this
was 20-inch. We werent starting with an eight-to-eight.
We did twelve-to-twenty. And I dont believe anyone
in this area has really tackled a bursting project of this
length or this size. The project allowed us to expand our
product offering and our capabilities. And that is always
a positive thing." Gibbs added that he looks forward
to the possibility of more bursting projects in the future.
Trenchless Technology,
September 2003
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