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Water Main Installation
Using Trenchless Methods
Water Main Installation - Trenchless
Overview:
• Introduction
• Design Considerations
o Geotechnical Investigations
o Subsurface Utilities
• Various Installation Methods
o Horizontal Directional Drill
o Horizontal Auger Bore
o Pipe Ram
o Microtunneling
o Pipe Burst
• Summary and Resources
Introduction
• Conventional Method - Open Cut
o
o
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Excavation and Shoring
Backfilling and Compaction
Pavement Restoration
• Alternative Method - Trenchless
o
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Excavation Pits are still needed
Therefore “Less Trench”
• Trenchless Construction and Renewal Methods
Trenchless Construction Methods
Horizontal Auger Boring,
Horizontal Directional Drilling, Pipe Ramming,
Microtunneling, In-line Replacement
Trenchless Renewal Methods
Slipline, Cured In Place,
Thermoformed Pipe, In-line
Replacement, Localized Repair
History
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1930 – early stages of HDD through vertical oil drilling
1936 – Horizontal Auger Boring originates in Coal Mining in PA
1971 – HDD introduced: 600 ft - 4” pipe river crossing in CA
1975 – Microtunneling developed in Japan
1977 – Pipe Bursting developed in United Kingdom
1984 – 12 HDD units exist
1986 – Establishment of ISTT
1990 – Formation of NASTT
2001 – Publication of HDD Consortium HDD Good Practices
2005 – Publication of ASCE HDD Manual of Practice
2015 – Thousands of HDD units exist today
North America – HDD developed from vertical steered oil well drilling, HAB developed from coal mining
Japan - Microtunneling evolved out of a demand for more sewer systems in the larger cities
United Kingdom - Trenchless technologies were used to replace and fix aging pipes from the Industrial Revolution
By 1986 Japanese, American, and European engineers banded together to officially categorize all of these
techniques under the umbrella of trenchless technology
Why Use Trenchless ?
FAMILY FEUD FAMILY FEUD FAMILY FEUD FAMILY FEUD FAMILY FEUD FAMILY FEUD FAMIL
ILY FEUD FAMILY FEUD FAMILY FEUD FAMILY FEUD FAMILY FEUD FAMILY FEUD FAMILY FE
Minimize Traffic /
Operations Disruption
24
Damage to Utilities /
Structures
11
Environmental Impact
20
Capital Cost
7
Road and Pavement
Damage
17
Heavy Construction /
Air Pollution
5
Site and Public Safety
14
Win
Lose
Cheer
Boo
Silence
Design Considerations
Geotechnical Investigations
• Conduct Geotechnical Borings
• Conduct away of proposed path
• Useful Geotech Information:
o
Water table
o
Presence of Rock / Cobbles
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Soil Strength and Stability
o
SPT tests at 5’ intervals
o
Grain Size Analyses
o
Unconfined compression tests
• Geotechnical Engineer Report
Slide 8 of 28
Design Considerations
Subsurface Utilities
Records Supplemented with Field Research
and Geophysical Methods
• Electro-Magnetic Methods
• Pipe and Cable Locators
• Ground Penetrating Radar
Precise horizontal and vertical location of
utilities obtained by the actual exposure.
• Vacuum Excavation Test Hole
• Utility Pipe is Exposed
HORIZONTAL DIRECTIONAL DRILL (HDD)
Horizontal Directional Drill (HDD)
Mini-HDD:
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Boring a small diameter pilot hole using a
cutting head with high pressure fluid.
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When the cutting head reaches the far side,
the pipe is then pulled into place behind a
reamer.
Short lengths up
to 12” pipe size, at
shallow depths
Maxi-HDD:
Longer lengths,
over 24” pipe size,
at greater depths
Horizontal Directional Drill
Process
1. Pilot bore
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Guided using steering head
2. Back Ream
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Multiple reams for larger pipes
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Drilling fluid maintains borehole
stability
3. Pullback
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Pipe to withstand pulling forces
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Rig to overcome frictional forces
Horizontal Directional Drill
Horizontal Directional Drill
Design
• Work Area Requirements
o
Small diameter – very little excavation
o
Large diameter – considerable area required

Rig Side: 20,000 sf

Pipe Side: Pre-assemble pipe string
Frac Tanks
Equipment Trailer
80’ to 180’
Boom truck
Solids Containers
Bore
Drill Pipe
Storage
Mud Tanks
and Pumps
150’ to 250’
Entry Pit
Drill Rig
Power
Unit
Control
Cab
Horizontal Directional Drill
Design
• Geometry
o
Entry Angles (8 o to 16 o)
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Exit Angles (5 o to 10 o )
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Minimum Depth
o
Bend Radius
Horizontal Directional Drill
Equipment and Materials
• Drill Bits
o
Slant faced bits
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Rotary rock bits
• Reamers
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Mixing reamers
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Compaction reamers
• Drilling Fluid Support System
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Drill Fluids

Transport cuttings
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Cleaning drill bits or reamers
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Cooling downhole tools
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Lubricate to reduce friction
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Stabilize borehole
Cleaning / Separation Systems
Horizontal Directional Drill
Troubleshooting
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Hydrofracture or “frac-out”
o
Shallow cover, thin drilling fluid, adjacent boreholes, fissures, utilities,
loose soil, gravels, high drilling pressures
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Loss of Circulation
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Collapse of Borehole
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Settlement / Surface Heave
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Obstructions
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Pipe Stuck in Borehole
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Possible Solutions:
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Increase fluid pressure / Adjust pumping rates
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Increase viscosity of drilling fluid
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Pull back and change alignment
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Change drill bit
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Install conductor casing
Horizontal Directional Drill
Summary Table
Mini
Midi
Maxi
Typical Application
Telecom, power cables, small
diameter pipe
Water and pipeline –
Rivers and Roadway
Water and pipeline –
Large River and Highway
Diameter Ranges
2 to 12 in
12 to 24 in
24 to 48 in
Typical Lengths
< 600 ft
< 1,000 ft
< 6,000 ft
Depth
< 15 ft
< 75 ft
< 200 ft
Working Space
minimal
400’ x 200’ rig side;
Pullback side varies
400’ x 200’ rig side;
Pullback side varies
Pipe Material
Typically HDPE
Typically Steel, HDPE, Fusible PVC
(restrained joint PVC and DI can also be used)
Soil Conditions
Clay : IDEAL
Significant rock: NO
Gravels / Small Rock: MARGINAL
All others soils: SUITABLE
Clay : IDEAL
Significant rock: MARGINAL
Gravels / Small Rock: MARGINAL
All others soils: SUITABLE
Productivity
600 ft / day
varies
Advantages
(1) Steering capability, (2) Drive and reception pits not required, (3) Long drive lengths
Limitations
(1) Disposal of slurry mixed cuttings, (2) Slurry migration
varies
HORIZONTAL AUGER BORE
Horizontal Auger Bore
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Pushing the pipe with a boring auger rotating within
the pipe to remove the spoil. Jacks can also be used
against a backstop.
Auger Bore
• Horizontal Auger Boring
o
Cradle Type
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Track Type
• Components (Track)
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Shaft and Track System
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Cutting Head
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Augers and Casing
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Boring Machine
Auger Bore
• Process
1.
Pit prep and installation of track
2.
Casing pipe and augers in front of Auger Machine
3.
Torque and Thrust transmitted to cutting head through
auger string
4.
Auger Machine retracted. New segment installed.
• Pit Sizes
o
Drive Shaft: Auger Machine + Casing Segment
o
Typical pit is 35 ft long (20’ casing) x 10 ft wide.
o
Sufficient Space at surface for loading / unloading
PIPE RAM
Pipe Ram
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Pushing the pipe using force transmitted by a percussion hammer attached to
the end of a pipe.
Pipe Ram
Cutting shoe welded to
leading edge
Ramming plate (ram cone or ram collets)
Pipe hammer is comprised of a double-acting pneumatically
driven piston, delivering up to 240 blows per minute
Leading edge typically open for
larger pipe
Bearing stands for pipe
Auger Bore / Pipe Ram
Summary Table
Auger Bore
Pipe Ram
Typical Application
Rail, Roadway ,or River crossing
Roadway or River crossing
Diameter Ranges
4 to 60 in
4 to 60 in
(120 in has been installed)
Typical Lengths
100 to 600 ft
200 to 300 ft
Working Space
Shafts at both ends. Drive shaft length = pipe + equip (typically 35’ x 12’).
Surface Area 50’ x 100’
Pipe Material
Casing: Steel
Carrier: Any material
Soil Conditions
Firm Sandy Clay: IDEAL
Sand below water: NO
Loose Sand above water: MARGINAL
Rock over 1/3 Dia: MARGINAL
Rock up to 1/3 Dia: SUITABLE
All others soils: SUITABLE
Productivity
Approx 6 ft per hr for 24” dia
(not including pit and auger prep)
Advantages
(1) Casing is installed as borehole
excavation takes place
(no borehole collapse)
(2) Versatile in variety of soil types
Limitations
(1) Requires substantial pits and accurate set-up
(2) May require dewatering
Soft Clays, Sands: IDEAL
Solid Rock: NO
Sand below water: MARGINAL
Hard Clays: MARGINAL
Weathered Rock: MARGINAL
All others soils: SUITABLE
(1) Can sometimes be performed in wet conditions
(2) Same as Auger Bore
MICROTUNNELING
Microtunneling
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Remotely controlled guided pipe jacking operation that does not require worker
entry in the tunnel.
Microtunneling
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Remotely controlled, guided,
pipe-jacking operation
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Pipes pushed behind
Microtunneling Boring Machine
(MTBM) using hydraulic jacks
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Provides continuous support to
excavation face through fluid
pressure
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Components:
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Crushing Cone
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Closed loop slurry system
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Slurry cleaning system
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Guidance System
Microtunneling
Rotation drive
Supply pipe
Conveyor pipe
Hydraulic Pump
Cutting wheel and
extraction tool
Crusher space
Microtunneling
Summary Table
Microtunneling
Diameter
Ranges
10 to 136 in (typical is 24 to 48 in)
Typical Lengths
500 to 1500 ft
Depth
5 ft minimum
Working Space
Varies, typically 30 ft x 100 ft
Pipe Material
Casing: Steel, RCP, or PCP
Carrier: Any material
Soil Conditions
Wet sand: IDEAL
Rock up to 1/3 Dia: MARGINAL
Large Rock: NO
All others soils: SUITABLE
Productivity
6ft per hr
Advantages
(1) Capable of very accurate lines and grades
(2) Can be performed in groundwater
(3) Worker entry not required
Limitations
(1) Problems caused by large boulders
(2) Equipment capital cost is high
PIPE BURST
Pipe Burst
Design Considerations
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Soil Conditions
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Adjacent utilities
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Pipe Bends
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Depth (surface heave)
General Rule
One foot of cover for
every inch
Of expansion
Pipe Burst
Summary Table
Pneumatic
Static
Typical
Application
In-line pipe replacement
Diameter Ranges
2 to 36 in
(48 in has been performed)
Typical Lengths
300 to 400 ft
Depth
Any depth of existing pipe
Working Space
Insertion pit 8’ x 15’
Insertion pit 8’ x 15’
(longer if cartridge method used)
Pipe Material
Typically HDPE
Typically HDPE, however, can be any material
including DI
Soil Conditions
Expandable Clay: IDEAL
Dense Clay and Sandstone: DIFFICULT
All others soils: SUITABLE
Productivity
Approx 50 to 100 ft per hr
(not including pit prep)
Advantages
(1) Ability to upsize pipes
(2) New pipe will follow alignment of existing
Limitations
(1) Reconnection of laterals by open cut is required
(2) Bypassing flow is required
(3) Potential ground displacement
Water Main Installation - Trenchless
Pipe Ramming
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Casing is installed as borehole
excavation takes place
Can be installed in wet conditions
Microtunneling
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Accurate lines and grades
Can be in groundwater
Worker entry not required
HDD
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Steering capability
Drive and reception
pits not required
Long drive lengths
Pipe Bursting
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Ability to upsize pipe
Follows alignment of
existing
Auger Boring
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Casing is installed as borehole excavation takes place
Versatile in variety of soil types
Water Main Installation - Trenchless
Summary and Take Away Points
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Trenchless means “Less Trench”
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Geotechnical and Subsurface investigations crucial
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HDD, HAB, MT, Pipe Ram, Pipe Burst all have
different advantages and limitations
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Plan for pitfalls: Frac-out, obstructions, settlement
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In many cases, Trenchless has favorable
economic costs due to less surface
restoration and MPT
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In almost all cases, Trenchless has
favorable social and environmental costs
Water Main Installation - Trenchless
Thank you
References:
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ISTT (International Society for Trenchless Technology)
NASTT (North American Society for Trenchless Technology)
Trenchless Technology by Mohammad Najafi
Horizontal Directional Drilling by David Willoughby
HDD Good Practices Guidelines by HDD Consortium
IPBA (International Pipe Bursting Association)
ASTM F1962 – Maxi-HDD for Placement of PE Pipe
TT Technologies
Prime Drilling
Herrenknecht Inc.
Presenter:
Ken Bienkowski, P.E.
Jacobs Engineering
(862) 242-7284
[email protected]