|
by Jim
Schill
|
The
Southern Pipeline crew used the static Grundoburst
pipe bursting system to burst and replace the 4- and
6-inch cast iron water main with 6-inch HDPE.
|
Louisville Water
Company, Louisville, KY provides over 120 million gallons
of water per day to over 240,000 residential, commercial
and industrial customers throughout the greater Louisville
area. Recently the water utility company began a major water
main rehabilitation project to replace sections of deteriorating
and tuberculated cast iron water main through pipe bursting.
To complete the project, pipeline contractor Southern Pipeline
Construction Company, Louisville, KY was contracted to burst
and replace several thousand feet of 4-inch and 6-inch cast
iron pipe using the Grundoburst 400G static pipe bursting
system from associate NUCA member TT Technologies, Aurora,
IL.
Several years earlier, Southern Pipeline, a multi-facetted
pipeline contractor with almost 50 years of experience,
performed a pilot project for Louisville water using pneumatic
bursting equipment. Static equipment was chosen for this
project.
Southern Pipeline CEO Stephen Mullins said, "Basically,
they [Louisville Water] wanted to do another pilot project,
this time with static bursting. Everyone was very impressed
with pneumatic bursting and this was an opportunity to demonstrate
the capabilities of the static system. Many sections of
the bursting took place under streets, parkways and highly
landscaped areas. All these areas benefited from the trenchless
application." In addition the method offered an opportunity
to attempt to chlorinate the lines before installing them.
This was some of the first pre-chlorination bursting work
performed in North America.
The
Static Bursting Process
Static
systems, unlike pneumatic bursting tools, do not incorporate
percussive action to break apart host pipes. Static bursting
systems utilize a configuration of specially designed bladed
rollers and an expander to split the host pipe and force
the fragmented pipe into the surrounding soil.
The process is simple. After the Grundoburst hydraulic bursting
unit is positioned in the exit pit, bursting rods are installed
through the host pipe and into the launch pit. Once at the
launch pit, crewmembers attach the bladed cutting wheels,
bursting head, expander and new HDPE to the bursting rods.
The entire configuration is then pulled back through the
host pipe by the bursting unit. The bladed cutting wheels
split the host pipe. The bursting head and expander displace
the burst host pipe while the new HDPE is pulled in simultaneously.
The unique system allows crews to chlorinate water mains
before installing them and makes bursting ductile iron and
steel pipes possible.
The Project
For the Louisville Water Company project, Southern Pipeline
burst and replaced 4-inch and 6-inch cast iron with 6-inch
High-Density Polyethylene (HDPE) pipe. The project was subdivided
into sections. According to Mullins, the first section was
representative of the total project.
He said, "The first section was under pavement on
24th Street. The 481-foot, 4-inch cast iron main needed
to be replaced with 6-inch HDPE. We divided the run in
half and placed the Grundoburst in the pit at the middle.
The first burst traveled north to south. After installing
the bursting rods, we pulled back the bladed rollers and
230 feet of 6-inch HDPE."
For the second burst, the Southern Pipeline crew used the
same pit, but turned the Grundoburst around 180 degrees
in order to burst from the other direction, south to north.
Bursting times for this section, as well as other sections,
ranged between two and three hours.
In addition, Southern Pipeline’s initial attempts at
pre-chlorinating the HDPE were met with promising results.
Mullins said, "Our pre-chlorination efforts during
this pilot project were hampered at first because of leak
in the pulling head section of the pipe, the point where
we actually attached the pipe to the pulling head. We installed
an extra seal weld on the inside of the pipe, and on subsequent
tries, pre-chlorination proved effective and past the testing."
Reaction
According
to Mullins everyone involved with the project was pleased
with the results. Southern Pipeline is currently working
on other static bursting projects and Mullins anticipates
more static bursting in the future.
|
