Most people are unfamiliar
with the term “trenchless pipe rehabilitation.” Some other names commonly used
are “no-dig,” “pipe breaking,” “trenchless technology,” and “trenchless pipeline
replacement.” No matter which name is used, it simply means splitting an old,
worn out pipe while inserting a new one ... all at the same time!
Trenchless technology includes many methods for
installing and rehabilitating underground utility systems with minimal surface
disruption. Basically, it refers to a method of replacing underground pipe work,
without digging long trenches that disrupt lawns, sidewalks, driveways, and just
about any other property feature that has the misfortune of existing above an
underground line!
The trenchless method installs the new pipe by
pulling it through the old pipe, even if the existing pipe is collapsed, behind
a special breaking head (or cone) that expands a clear channel ahead of the new
pipe as it travels underground. One small pit is all that is necessary for most
jobs in order to feed the new pipe into the ground … a compact but powerful
pulling machine is located at the destination point, often inside a building, to
pull the pipe in from the pit. Here are a few methods used to perform
trenchless pipe rehabilitation.
RAMMING METHOD
Dynamic ramming method uses unsteered ramming
with pipe propulsion, along with the use of a pneumatic pipe-ramming machine.
With these, open steel pipes can be laid beneath railway tracks, highways, and
rivers, either as protection or product pipes, with diameters up to 2000 mm for
lengths of up to 80 m in the soil without using pressing abutments. The ram is
driven by compressed air and has cotter segments to establish a connection
between the machine and the pipe. Due to the two gaps in the soil removal cone
or adapters, part of the tension of the spoil carried along is released. The
application of cotter segments prevents the pipes from flaring up and enables
high-quality butt welds of the single pipe lengths. The casing friction of the
inner or outer pipe is reduced by bentonite cutting shoes that simplify pipe
propulsion by lubricating the pipe. The minimal displacement volume in the area
of the cutting shoe eliminates the risk of road surface heave, and means that
work can commence even from shallow pit depths. Advantages of the method include
surfaces worth conserving are not broken, restoration is not required, low
social costs, acknowledged procedure, short set-up times, short pipe-laying
times, no pressing abutment, no conveyor spiral, no flooding when working on
river crossings, minimal covering, no elaborate pits, simple operation
technique, and adaptation to all pipe diameters with a special ram cone.
TRENCHLESS PARRALLEL NO-DIG TECHNIQUE
The trenchless parallel no-dig technique is a
further developed and refined version of the water flush drilling method that
has been developed by Stadtwerke Schwerte GmbH. It solves the problem of space
availability for all sorts of utility lines, by considerably reducing space both
above and below ground, thus making it possible to lay a bundle of pipes in a
one-step operation without twisting, and trenches in precisely defined
distances.
TRENCHLESS PIPE REHABILITATION
Trenchless pipe rehabilitation refers to the
method of trenchless
pipe replacement through the renewal method, which includes:
DYNAMIC PIPE BURSTING
In the method of dynamic pipe bursting, the
bursting machine is pulled by a winch through the old pipe meant to be renewed.
During this procedure, the old pipe is destroyed by dynamic impact energy, and
the fractured particles are pushed into the surrounding soil, while the new
line—in the same width or one size larger—is pulled in at the same time.
PIPE EATING BASED ON MICROTUNELING
Pipe eating is a replacement technique based on
microtunneling,
where the defective pipe is excavated together with the surrounding ground, as
it would be for a new installation. The pipe eating shield is pushed forward
along the route of the existing pipeline using hydraulic jacks, located in the
drive shaft. The replacement pipes are connected to the back of the tunneling
shield. On completion of the drive length, the pipe eating shield is recovered
at the reception shaft, leaving a new pipeline in place of the defective pipe.
PIPE EXTRACTION METHOD WITH GRUNDOBURST
Pipe extraction method with grundoburst is the
method wherein damaged gas and water lines can be easily replaced by new pipes
in the same bore path.
PIPE SPLITTING METHOD FOR TRENCHLESS PIPE REPLACEMENT
Pipe splitting method solves the problem of lead
pipes being replaced by plastic pipes to supply potable water. This method was
developed by the Water Supply Company of Berlin, in order to carry out
trenchless lead pipe replacement within the field of house connections.
STATIC PIPE BURSTING METHOD
Static pipe bursting method with the patented
Grundoburst is used to replace old pipes, especially in sensitive soils within
the vicinity of other external lines. It is often used for the renewal of
potable water lines where stems are pushed through the old line first. The old
pipeline is actually cut open by the roller blade, immediately followed by the
expansion head. Advantages of this method include: path of the old pipe can be
used; bursts grey cast iron, asbestos-cement, stoneware, concrete, and plastic;
pipe bursting can also cut ductile grey cast iron and steel new pipe with new
longevity improvement of the hydraulic capacity, because the new pipe to be
installed is one or two sizes larger; no reduction of the cross section;
applicable for all types of damage; good bedding conditions; short equipping
time and simple operation technique; and high daily capacity of up to 150 m.
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