Directional Boring Overcomes Tough HDD Project With Percussive
Pipe Ramming Power
reaching an impasse during pullback, the Arrow Directional
Boring crew attached a Grundoram pneumatic pipe rammer to
the end of the 1,000-ft, 18-inch HDPE pipe string. The rammers
percussive action was able to free the immobilized pipe,
allowing successful installation.
the last several years, the EPA and other organizations have
taken a very aggressive stance when it comes to sanitary sewer
overflows (SSOs) and correcting the problems of inflow and
infiltration (I & I). The EPA
has issued several high profile administrative orders regarding
these problems. Recently, the city
of West Palm Beach, Fla. faced an administrative order regarding
discharge from its sanitary sewer mains.
As a solution to the problem, the city turned to NUCA contractor
Arrow Directional Boring, Coral Springs, Fla. for the installation
of a sanitary sewer force main. The multi-faceted contractor specializes
in trenchless technology including pipe ramming, pipe bursting,
horizontal boring and directional drilling. For the project in
West Palm Beach, the contractor combined pipe ramming with directional
drilling to overcome tough working conditions.
Arrow Directional Boring Vice President
Jeff Blake said, "The
city was experiencing problems with I & I in its sanitary sewer
system. During periods of heavy rain, the sanitary system would
back-up into the gravity system and top the manholes. This was especially
troubling because sewage would eventually find its way into the
inter-coastal waterway. The force main system is designed to eliminate
this problem by increasing the systems capacity."
The project called for the installation of 11,000 feet of 12- and
18-inch HDPE force main through directional drilling. The Arrow
crew divided the runs into 1,000-foot segments. When tough soil
conditions and extreme depth halted one pullback 100 feet short
of completion, Blake opted to assist the pullback with the percussive
power of a Grundoram pipe rammer from Associate NUCA member TT Technologies,
Aurora, Ill, in hopes of successfully completing the bore.
Several pipe ramming techniques have been developed 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.
TT Technologies product specialist Frank Fresneda 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.
Were actually seeing drilling contractors bring pneumatic
pipe rammers to job sites as a kind of insurance policy. Its
been very positive for the industry and worked well in West Palm
One of the most difficult drilling segments of the project took
place under the northbound lane of a highly traveled roadway, at
a depth of 15 feet. The fine sand conditions compounded the problem,
making it difficult to maintain a bore-hole.
According to Blake the crew anticipated problems for that particular
installation of 18-inch HDPE. He said, "During back-reaming
we kept running into an area that was giving us a hard time, right
around the 900-foot mark. We couldnt find anything specific
however. On our first back-ream, which was 18 inches, we got hung
up. We were going to use a 32-inch back-reamer, but at that point
decided to use a more aggressive 27-inch reamer; and we were able
to get through the tough section. Then we decided to pull the pipe
in with the 32-inch reamer, but were stopped about 100 feet short
Blake had actually utilized the pullback assist technique on previous
projects. After calling Fresneda and explaining the situation, an18-inch
diameter Grundoram Goliath pneumatic pipe rammer arrived on site
the next day. The Arrow crew attached the pipe rammer to the end
of the HDPE product pipe and began ramming. After an hour, the percussive
action of the pipe rammer began to free the HDPE. The Arrow crew
was then able to pull the pipe into place with the drill rig, without
Blake said, "The hammer worked extremely well for the directional
assist. Everyone involved with the project was really pleased with
Fresneda said, "Jeff [Blake] and the entire Arrow crew are
top-notch contractors. Theyve been in difficult situations
before, but they have a tremendous amount of experience and are
able to find the right solutions to get through the tough projects."
NUCA, July 2002