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by Jim Schill
In the past,
the rehabilitation and replacement of sewer service laterals
was perceived as difficult, expensive and intrusive.
With lateral lines running underneath yards, business
entryways, sidewalks, etc. open cut trenching is usually
the least attractive lateral rehab option. Most laterals
continue on into some type of street or roadway where
trenching is even less popular among motorists and public
safety officials.
And that is just part of the lateral replacement issue.
According to Collins Orton, Trenchless Equipment Specialist,
TT Technologies, Aurora, Ill., the lateral problem is
being addressed at all levels. He said, “According to the EPA
over half of the sewer systems nationwide are beyond the mid-way point in their
life expectancy. Seventy percent of utilities throughout the country are already
experiencing some problems associated with inflow and infiltration. With laterals
typically making up half of those systems, it’s not hard to determine where
attention needs to be focused.”
Many municipalities are now offering lateral replacement
programs that limit or even eliminate the homeowners fiscal
responsibility for replacing the lateral, an indication
of the seriousness of the I&I problem in some areas.
But lateral replacement is not just a municipal/residential
issue. Companies, corporations, factories, restaurants,
etc. all face the problems caused by failing lateral service
lines whether they are sewer related or not.
While every lateral replacement situation poses its own unique challenges, a
trenchless rehab option is almost always preferable in those situations. However,
many trenchless options are not applicable to lateral replacement. Pipe bursting
offers a viable solution to the lateral replacement challenges. The following
case studies highlight the various circumstances contractors find themselves
in when replacing lateral. Case
Study #1: Carpet Outlet Store; San Diego, CA
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The
Underground Solutions crew was able to burst and
replace 120-foot, 4-inch cast iron lateral line
with 4-inch HDPE using static bursting. Through
the static process, the crew was able to overcome
a 45-degree bend in the exiting line.
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The tenant at this particular mall was new to the property and had just established
a retail carpet and tile store. The existing lateral sewer line for the location
had failed via corrosion and age causing exfiltration of water into the surrounding
ground soil whenever the bathrooms were used. The property management company
provided the tenant with an outdoor portable bathroom until a solution to the
problem could be found. With grand opening pending, the tenant was anxious to
get rid of the portable bathroom, not only for themselves, but for their customers
as well.
According to Underground Solutions sales and operations
Manager Dave Munson, San Diego, CA, everyone was concerned
about fixing the issue. He said, “Because
of the failure in the cast iron lateral, the line regularly was stopping
up and causing over flow situations in the building’s
bathrooms. The property management firm was desperate
for a means to replace the line without digging
up the floor of the new carpet and tile store. The portable bathroom situation
certainly wasn’t the answer for a retail outlet trying to impress customers.”
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Another
example of extremely tight working conditions.
The launch pit for this project was actually inside
of the building. Pictured is the fused HDPE running
down one of the aisles of the store.
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The project
consisted of replacing an existing 4-inch cast iron lateral
that ran from the bathroom area of the tenants building
outside to an existing clean
out. The lateral was approximately 120 linear feet and had a 45-degree
bend about halfway through the run. For the project Munson
chose the Grundotugger lateral
pipe bursting system from TT Technologies, Aurora, Ill.
Munson
said the Underground Solutions crew prepared a “precisely carved” launch
pit inside the store and an exit pit outside of the building using a vacuum
excavation system. Once prepared, the crew fused together
the necessary 4-inch High Density
Polyethylene pipe (HDPE) and connected the bursting head and expander.
The tugger unit was positioned in the exit pit. Once
the
winch line was in place the bursting
proceeded without incident. The entire burst took a little over one hour.
Munson said, “The fact that the lateral ran underneath
a retail store and was considered a dire emergency
by the client really made this project unique.
The property management firm was under the gun to solve the problem. The
solution was very effective. Combining state-of-the-art
equipment in the vacuum excavation
rig and the Grundotugger proved key to doing a fast, clean, precise and
safe job.”
The Continued
Growth of Lateral Pipe Bursting
According Orton, the acceptance
of lateral pipe bursting has taken quite a bit of effort.
He said, “We have
been bursting laterals for years, but because of bursting’s
association with large diameter pipes, contractors that
specialized in small diameter work never considered it.
There was also a bigger is better mentality in the industry
among equipment manufacturers. But, as the industry has
now broadened it vision to include laterals, the manufacturing
community has responded with high powered, highly portable
lateral bursting equipment.”
Orton also noted that improvements in lateral bursting
equipment have made the method accessible to everyone from
specialty to general contractors. Orton said, “The
new lateral bursting equipment is very portable, but doesn’t compromise
on power. It’s also easy to use. Both static and pneumatic lateral bursting
systems can be easily transported in most pick-up trucks. They only require a
minimal crew compliment to operate. And they really get the job done well. With
the big push for lateral replacement, the timing of some of this equipment couldn’t
be better.”
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Residential
lateral replacement often comes about because of
tree root intrusion. The existing VCP line in this
project suffered from severe root intrusion.
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Case Study #
2: Residential Lateral Replacement; Ventura, CA
What once was considered a very difficult pipe bursting application, lateral
replacement has now become one of the easiest ways to get into pipe bursting.
West Coast Plumbing, Ventura, CA recently made the leap into lateral pipe bursting
on what could be considered a textbook lateral replacement.
For their first burst, West Coast Plumbing President Doug Ingram utilized the
Grundotugger static system. The project consisted of bursting and replacing a
4-inch residential sewer lateral with 4-inch HDPE. The existing 40-foot VCP line
was suffering from sever tree root intrusion and had been a reoccurring problem
for the residents.
TT Technologies Pipe Bursting specialist Paul Rogers was
on hand to provide the West Coast crew with technical
support during their first burst. He said, “The
crew did a great job. They caught on to everything very quickly and the job
went very smoothly.”
The West Coast crew began operations by excavating launch and exit pits at either
end of the lateral. Crews then rodded the decaying line and pulled the winch
cable in place. The Grundotugger unit was placed in the exit pit, while the new
HDPE was fused and positioned at the launch pit. Crews then focused on attaching
the expander to the fused pipe and connecting the entire configuration to the
winch line. Once connected, bursting was ready to begin. Thirty minutes later
the new HDPE was in place and the crew began connecting the new lateral to the
house and mainline.
Lateral
Bursting Benefits
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The
deteriorated 4-inch VCP line was bursting and replaced
with 4-inch HDPE. Crews kept disruption to a minimum
by using the static pipe bursting method.
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Pipe
bursting is well suited for lateral replacement. It is capable
of replacing relatively small diameter pipe and allows for
increase or upsize of the original host pipe diameter. That
fact alone is extremely valuable on jobs where lines are
being replaced because of capacity issues.
The method is trenchless, which is of particular significance in a lateral replacement
situation. Lateral replacement can be a sensitive issue on a municipal level
because laterals are most often considered a private, residential issue. Convincing
or mandating that a private homeowner replace their sewer lateral is difficult
enough. Offering them a trenchless option that can mitigate damage to trees,
driveways, sidewalks and landscaping can help soften the blow. In the urban setting
when there is little right-of-way and a lot of concrete and asphalt, trenchless
lateral pipe bursting can have a tremendous impact by limiting cost and disruption.
Case Study #
3: Grease Lateral Line, Hotel Restaurant; San Jose, CA
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The
Viso crew had to contend with an extremely tight
work area. Pictured is the hydraulic power pack
used to power the Grundotugger static pipe bursting
system. Note the cramped conditions.
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Sometimes
it’s not yards or landscaping that worry contractors replacing
laterals, it’s alleyways and sidewalks. Recently utility contractor James
J. Viso Engineering, Santa Clara, CA took on a difficult lateral replacement
at a hotel/restaurant in downtown San Jose. According to Viso Vice President,
Joe Viso, tight working conditions made the project rather challenging. He said, “This
project was downtown. There is no frontage; the hotel is on the sidewalk. The
4-inch cast iron line came out of the back of the hotel, from the restaurant,
ran approximately 40 feet to a grease interceptor, then ran back under the
hotel and to a main located in the front of the hotel in the street.”
Viso was contracted to replace the section of lateral
that ran from the grease
interceptor back to the hotel, the “downstream” section, with 4-inch
HDPE. That 40-foot section of cast iron pipe was in very bad shape. According
to Viso, attempts at video taping the line were hampered by its poor condition.
It was completely collapsed in several locations.
The Viso crew excavated a launch pit next to the grease
interceptor and an exit pit next to the hotel. Space
was very tight. The launch pit measured approximately
six feet long by a foot wide and the exit measured feet four feet by four feet.
The pits needed to be constructed to minimal dimensions to accommodate the
hotel’s
above ground mechanical equipment and below ground utilities.
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New
lateral bursting systems give contractors the ability
to burst and replace 4-inch and 6-inch laterals
up to 150 feet in length. The systems are powerful
and potable.
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In
addition to the host pipe condition and a cramped working
area, Viso had to contend with poor soil conditions.
He
said, “The soil was very soft and
unstable. When we first started, it just sucked the tugger in. What we decided
to do was take some two inch steel pipe and drive it into the ground to brace
the tugger. The ground was so soft we drove in about eight or ten feet of
pipe with no problem. I thought there was no way it
would hold, but it did and we
were able to burst without problems.” Lateral
Replacement Future
All of the contractors involved
with the aforementioned projects are aware of the potential
that lateral replacement represents. According to Orton,
the market is just beginning to develop. He said, “We’re seeing the very start
of a lateral replacement frenzy. Failing laterals always need to be replaced,
but with I&I mandates coming down, the pressure is on in many areas to rectify
the problems. As main lines get replaced, laterals are soon to follow. There
is a lot of work to be done on the horizon.”
Special thanks to the following individuals
for contributing to this article:
Dave Munson, Sales and Operations Manager, Underground
Solutions, Inc., San Diego, CA
Doug Ingram, President, West Coast Plumbing, Ventura,
CA
Joe Viso, Vice President, James J. Viso Engineering,
Santa Clara, CA
Collins Orton, Trenchless Specialist, TT Technologies,
Aurora, Ill.
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