Pipe ramming continues to
demonstrate its versatility, especially when it is used in concert
with a directional drilling application. James Daigle, Division
Manager with Sunland Construction, Inc. Eunice, LA, knows the
value that pipe ramming adds when working on difficult, large
diameter HDD projects. Recently, Daigle and his crews were able
to complete a difficult large diameter HDD river crossing with
the help of pipe ramming HDD assist techniques in Charleston,
SC.
Sunland
Construction crews used a barge to transport
the Grundoram Taurus pneumatic pipe rammer to
the job site for the HDD Assist operation. The
crew was attempting a 5,400-ft pullback of 40-in
casing when pullback stalled 700 feet short.
|
|
Several
pipe ramming techniques have been developed over
the last several years to successfully remove stuck
drill stems, assist directional drill rigs during
difficult pullbacks, free immobilized product pipes
and even salvage failed bores by removing stuck
pipe from the ground.
|
|
During
the pullback assist the Grundoram pipe rammer is
placed at the end of the pipe string. The dynamic
energy of the rammer is transferred down the pipe
string to the lead end of the pipe. In many cases
the percussive force is enough to free the stuck
pipe.
|
|
Within
ten minute of utilizing the pipe rammer, the immobilized
pipe began moving and pullback was successfully
completed. Sunland preordered the pipe rammer as
an “insurance policy” for this difficult
bore.
|
|
The
Sunland Construction crews used a self-manufactured
700,000 lb capacity drill rig for the difficult
water main installation project under the Cooper
River in South Carolina.
|
|
| |
Daigle said, “Charleston
Water System saw the need for additional water supply because
of population growth and increasing demand. We were involved
in two of the HDD portions of the project, one under Coulter
Creek and the other under the Cooper River. We were subcontracted
for the project by the prime contractor Skibeck Pipeline Company,
Inc., Randolph, New York.”
The Clouter Creek and Cooper River bores both called for the
installation of a 40-inch diameter steel water main 0.700-inch
wall thickness. The Clouter Creek bore measured 2,739 feet, while
the Cooper River bore was almost twice the distance at 5,481
feet. Both bores were part of a larger water main installation
project for the Charleston Water System (CWS), Charleston, SC.
Anticipating
the potential for challenging conditions, Daigle contacted
pipe ramming specialist Brian Hunter, TT Technologies, Aurora,
Ill and scheduled the delivery of a pneumatic pipe ramming
tool. Hunter said, “We have worked on several highly challenging
directional drilling projects with
James (Daigle) and the Sunland
Construction crews. Having a pipe ramming tool on site during
a difficult pullback can really improve chances for success when
things don’t go as planned. In this particular situation
James was prepared and called ahead to have the rammer ready
in case it was needed.”
For the project Daigle had a 24-inch diameter Grundoram Taurus
pneumatic pipe rammer delivered from TT Technologies.
According to the its Web site, the Charleston Water System has
been providing potable water to the residents of the Charleston
area since 1917. Before the water utility was formed, residents
got their water through wells and cisterns. But poor sanitation
and contamination forced city leaders to organize and find
safer, more reliable sources of water.
Today the Charleston Water System provides potable to over 101,000
residential accounts, servicing over 350,000 people. That service
also includes wholesale service to the US Department of Defense
and several surrounding communities. In early 2006, the CWS Board
approved a $155.5 million capital
improvement program to meet
rising demands on its water and wastewater infrastructure.
A portion of that program includes the 40-inch diameter water
main that Daigle and Sunland Construction were subcontracted
to install.
Sunland Construction was incorporated in 1974 in Louisiana.
Since then, the company has become one of the largest pipeline
contractors in the United States with an average workforce of
600 people and a peak workforce topping 1,600 employees. The
directional drilling division of Sunland was created in 1991
and is now considered a premier directional drilling provider.
The CWS project would put their skills to
the test.
Directional drilling operations under water face distinct challenges.
Difficult soil conditions under river bottoms, lakes and even
an ocean combined with the weight of the pipe and the hydrostatic
pressure of the water itself can create problems during drilling
applications. Directional changes within the bore itself can
compound those problems. Reaching a point during
product pullback
where the pulling forces required to pull in the pipe exceed
maximum capability (a condition often referred to as hydrolock)
is one potential problem.
Daigle said, “The Clouter Creek bore was ultimately completed
without issues. But we had two problems on the Cooper River bore.
The first was the soil conditions. We had marl in that area.
Marl is a really heavy clay type soil, a very dense material
and we drilled through several thousand feet of that. We also
had to contend with several deviations in elevation and alignment
during the bore that added to the difficulty level.” For
the project, Sunland used a self-manufactured 700,000 lb capacity
drill rig.
Daigle continued, “We set up on shore, on Virginia Avenue
and drilled out, under an existing refinery, beyond the refinery,
under the river, and then exited out on the Corp of Engineers
landfill. It’s basically an area that is used to accumulate
the spoils, silts, and soil that is taken out of the river when
it’s dredged. The river is dredged periodically for shipping
traffic in order to maintain the proper water depth.
The product pipe
was actually built by Skibeck on the spoil pile area. After
the pilot bore was complete, we began the backreaming process.
We made five reamer passes. We reamed a 20-inch, a 32-inch,
a 36-inch, a 42-inch and finally a 54-inch. At that point,
we attached the 5,500 feet of 40-inch steel and began pullback.”
The pullback
began at seven o’clock in the morning on
a Tuesday. By midnight, the pipe became lodged and pullback stopped
700 feet short of a successful bore. The crew shut down operations
for the night. However, because Daigle had pre-ordered the Grundoram
Taurus, it was scheduled to be on site the next morning at eight
o’clock. An HDD Assist
operation was planned.
According to TT Technologies National Sales Manager Brian Mattson,
several pipe ramming techniques have been developed by TT Technologies
and its partner contractors over the last few years to assist
directional drill rigs in difficult situations. The techniques
have been used to successfully remove stuck drill stems, assist
directional drill rigs during difficult pullbacks, free immobilized
product pipes and even salvage failed bores by removing stuck
pipe from the ground.
Mattson said, “By utilizing the percussive action of the
Grundoram pipe rammer we can really help drilling operations.
These techniques can help avert costly situations where product
pipes or drill stems get stuck. We’re actually seeing drilling
contractors bring pneumatic pipe rammers to job sites as a kind
of insurance policy. It’s been very positive for the industry.”
After the pipe
ramming tool arrived on site, it was loaded on a barge with
two 1600 cfm air compressors and towed to the spoil pile area.
According to Hunter the HDD pullback assist procedure is fairly
simple to understand. He said, “The whole idea
behind a pullback assist is to utilize the percussive action
of the rammer to free the stuck pipe. The rammer is attached
to the back of the pipe string. The dynamic energy of the rammer
is transferred down the pipe string to the lead end of the pipe.
In many cases the dynamic energy generated by the rammer is enough
to free the stuck pipe and get it moving again. Sometimes it
takes just a matter of minutes.”
The 24-inch diameter
rammer was connected to the end of the 40-inch diameter pipe
string through a series of segmented ram cones. Once the connection
was complete the rammer was started and the HDD assist was
underway. Daigle said, “It was probably
about 10 minutes after tapping on the pipe with the rammer that
it became dislodged and we were able to pullback the remaining
700 feet without trouble.”
According to Hunter, everyone associated with the project was
pleased with the results. He said, “The timing of everything
really worked out. The Sunland Construction crews are excellent
to work with. And ultimately they got their project completed
on time. Having the rammer ready to go certainly helped out.”
Daigle said, “Having the rammer available for an HDD assist
on risky projects is basically an insurance policy. At least
that’s the way I view it. That’s why I pre-ordered
it for this one. I didn’t mind spending the extra dollars
to have it on site. Having it on site meant that we avoided having
to wait through several days of shipping and set up. I was actually
able to accomplish what I needed to accomplish on time, rather
than having the entire job shut down for three days waiting for
the tool to arrive. It was well worth it.”
Jim Schill
Technical Writer
Mankato, MN
Trenchless Technology ,
November 2006
|
