This document provides an overview of trenchless technology, also known as no-dig technique, for installing underground pipes and cables with minimal excavation. It describes common trenchless methods like pipe bursting, microtunneling, and horizontal directional drilling. Open trench installation is compared, noting advantages of trenchless include less environmental and traffic disruption. The document also gives examples of trenchless projects in India and concludes that this technology allows underground installation while retaining resources and limiting surface impacts.

1. TRENCHLESS TECHNOLOGY
(No-Dig Technique)
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Knowledge.

2. TABLE OF CONTENTS
• Introduction
• Open Trench Method
• Advantages of No-Dig Technology
• Trenchless vs Open cut Method
• Methods of Trenchless Technology
• Pipe Bursting
• Micro-Tunneling
• Horizontal Directional Drilling
• Trenchless Technology in INDIA
• Conclusion

3. INTRODUCTION
Trench less technology is the science of installing, repairing and
renewing underground pipes, ducts and cables using techniques
which minimize or eliminate the need for excavation.
It is basically making a tunnel below the surface and installing
service lines like water or gas pipes, electric or telecommunication
cables etc. without any disruption to the public.
 It can reduce environmental damage, social costs and produce
an alternative method to open trench method of installation,
renewal and repair .
Trenchless technology is a type of subsurface construction
work that requires few trenches or no continuous trenches.

4. Open Trench Method
 A trench is excavated
running parallel to the old
water main and the new pipe
is laid in this trench. The
technique is suitable for all
pipe materials, however,
disruption to road users is
greatest and costs of
reinstallment can be high.

5.  In the picture, an open
trench water mains
renewal is in progress in
a residential area . The
trench has been
excavated and the new
pipe is in the process of
being installed.

6. Vs
TRENCHLESS OPEN-CUT

7. DIFFICULTIES IN OPEN TRENCH
METHOD
 As the open trench is going to create obstruction on roads i.e. busy areas,
diversions have to be provided before start of any digging work.
As the obstruction is created, the traffic has to be rerouted causing traffic jams.
 Original users of the road have to undergo hardships in the form of additional
travel as well as time.
 Another difficulty, which is
encountered very often is the
damage caused to other service
lines or cables present underground,
providing temporary supports to
these lines during the construction
is cumbersome and costly affair.

8.  While cutting open trenches, trees, shrubs, gardens etc. may have to be
destroyed damaging the environment.
 If any rehabilitation or renovation is required, the trenches once cut and refilled
should again be cut through out and refilled causing difficulties to the public i.e
cutting and refilling is required at frequent times.
 Trenches left open
overnight should be fenced
and barricaded. Hand of
mechanical signs should be
used where necessary.

9. ADVANTAGES OF NO-DIG TECHNOLOGY
•It reduces damages of valuable surface.
•It reduces the danger of improperly compacted excavations.
•It saves resources.
•It is accident free.
•It avoids traffic jam.
•It saves underground space (pipe busting).
•It reduces the impact on the environment.
•It is possible to lay service lines across railway track, narrow lanes etc. When
open trenching is impossible.
•Presence of a canal, pond, river etc. across the root poses no problems to the
trench less technology systems.
•Without disturbing the traffic and life on the surface, the lines can be laid
below ground in a much shorter time by using this technology.
•For replacement, repair and rehabilitation of old water and sewer lines in
cities, it is very helpful to use trench less technology without disturbing the
normal life on the surface.

10. Trenchless v/s Open-Cut
Open Cut Construction Trenchless Construction
Overcut for
Trenchless Installations
Import Material
for Open Cut Construction
Undisturbed Native Material
Roadway
Reconstruction

11. ADVANTAGES & DISADVANTAGES
 Disruption: Traffic delays are reduced or eliminated, as is heavy truck traffic
associated with culvert excavation deep below the roadway.
 Speed of installation: Construction often takes less time, regardless of the
road fill depth.
 Less engineering: Less surveying, fewer design calculations, and fewer
drawings and specifications may be required.
 Safety: Many safety concerns associated with steep-excavation slopes, work
inside trench boxes, and worker exposure to traffic may be eliminated or
reduced.
 Environmental effects: Less soil is disturbed so impacts on adjacent
organisms and water bodies can be reduced significantly.

12. TRENCHLESS TECHNOLOGY METHODS
1. Rehabilitation & Renovation
1.1) Pipe bursting
1.2) Pipe eating
1.3) Retaining the existing pipes
1.4) Localized repair
2. New installation
2.1) Micro-tunneling
2.2) Horizontal directional drilling
2.3) Short drive system
2.4) Guided drilling

13. Pipe Bursting
 In this method an existing pipeline can be replaced with a pipeline of the
same or larger dimension without opening up the ground.
 It is especially useful in areas where the load on the system is more than the
existing pipe can handle and replacement is required.
 The method uses a mole as a bursting head that is drawn through the
existing pipe crushing it as it moves forward and replacing it with a new PE
(polyethylene) pipe.
 The main advantage of this system is that a small power source can be used
to drive the mole with minimum time.
 Upsizing from 100mm diameter to 225mm diameter is now well established,
and pipes of up to 600mm diameter have been replaced.

14. Pipe bursting is of 2 types :
 Pneumatic Pipe Bursting
Static/Hydraulic Pipe Bursting

15. Micro Tunneling
 Micro tunneling is a term which is used to describe remotely controlled
mechanical tunneling systems where the soil is removed from the cutting
head with in the new pipe line which is advanced by pipe jacking.
 The cutting head has to be carefully selected to deal with the expected
ground conditions, with the appropriate cutting tools and crushing devices for
the range of gravels, sands, slits, and clays.
 The only excavating required from the service is for drive and reception
shafts. Spoil may be removed from the face by an auger running through the
newly installed pipeline to a skip in the base of the drive shaft.
 Water may be used to convert the soil into slurry at the cutting face. The
slurry is then pumped to the surface where the solids are separated before
disposal.

16.  Micro tunneling is used extensively for sewerage work where surface
disruption has to be minimized. It provides the necessary degree of accuracy in
gravity lines.
 Considerable advances have been made in recent years. Machines are now
available to drive 100m or more in soft ground for sizes of 100mm diameter
pipes from drive shafts with a high degree of accuracy.

18. Horizontal Directional Drilling
 It involves steer able tunneling systems for both small and large diameter
lines. It is two stage process.
 First stage consists of drilling a small diameter pilot hole along the desired
centerline of a proposed line.
 In the second stage the pilot hole is enlarged to the desired diameter to
accommodate the utility line and to pull the utility line through the enlarged hole.
 Horizontal drilling systems are nowadays widely used for installing pressure
pipes under major obstacles such a motor way intersections, large rivers and
airports runways.

19.  Pilot hole is 3 inches in
diameter and is drilled with an
inclined carriage, typically
between 5 to 30 degrees which
pushes the drill rod into the
ground.
Entry of the pilot drill pipe or
string is often 12 degrees ,
pilot hole continues at a 12
degree angle until it passes to
level out horizontally under the
obstacle. Once the hole has
passed obstacle it rises the far
side with an 8 degrees.
Bentonite drilling mud is
pumped down the centre of the
drill rods. The drill head
consists of either a jetting head
or a drill bit.

20. Open cut
•In a 1000’ long project, 12” pipe
replacement
• Export /import of soil = over 500 truck trips

21. Trenchless (Pipe Bursting)
•In a 1000’ long project
• Pits every 300 feet (25’x10’x10’)
• Co-located at manholes
• Export/import of soil = ~75 truck trips
LESS SOCIAL
IMPACT

22. TRENCHLESS TECHNOLOGY: IN INDIA
•Brihan Mumbai municipal corporation has used micro tunneling for the construction
of 3m diameter tunnel.
•MTNL has installed large telephone cables of approximately 185 km length in Delhi &
Kolkata by this method.
•Pipe line laying below river bed is impossible by open trench method, pipe line laying
below Hoogly river by this technique is sufficient to say its importance.
•In Kolkata 700m length and 0.762 diameter iron pipe was repaired which started
leakage.
•Laying of 18’ dia. Pipe of HBJ (Hazira-Bijaipur-Jagdishpur) across Yamuna river is
accomplished by this technique.
•1719m gas pipeline was laid 35m below Godavari river in 1994.
•24’ diameter and 350 long pipes were successfully installed by Indian oil corporation
for Panipat refinery.

23. Conclusion
• By adopting this technology we can successfully
implement pipes under the surface without
making any disruptions to the environment and
public.
This enables us to retain our available
resources, thereby, keeping the earth
unexcavated.

24. REFERENCES
• “Trenchless Technology” by Mr. S.R NABEEL.
• “Micro-tunneling Technology” by Mr. Shyamal Sarkar.
• “Trenchless Repairing” by Woo Seok Chin, Jae Wook
Kwon, & Dai Gil Lee.
• “Trenchless Technology Solutions” by Mr. Robert
Zlokovitz.
• “Trenchless technology for rehabilitation of sewers” by
Alfred Angerlehner & Christian Dobretsberger.
• “Summary of Trenchless Technology” by Rob Piehl.