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Introduction toTrenchless Methods
Presented by
Glenn M. Boyce, PhD, PE
Senior Associates
April 21, 2009
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Presentation Objectives
Provide a better understandingof trenchless methods used fornew installations
Learn the advantages and
limitations of the methods Discuss contractor
qualifications
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Types of Infrastructure
Gas Pressure
Water Pressure Sewer Gravity Drainage Gravity Power Non-gravity Communications Non-gravity
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Trenchless Methods Impact moling Pipe ramming Auger boring Pilot tube Pipe jacking / Microtunneling
Conventional tunneling Horizontal directional drilling Pipe bursting
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Generic Size and Length Method Size Length
Moling 2 - 12 150
Ramming 8 - 72 300 Auger Bore 8 - 60 250 Pilot Tube 6 - 42 300 Microtunneling 12 - 108 1,500 Pipe Jacking >54 3,000 HDD 2 - 48 6,500 Tunneling >60 Any length
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What to Do?
Choose the right method Use established Standards Collect information/investigate Plan ahead
Conduct risk assessments Include mechanisms to handle
conflicts
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Auger Boring
Road crossings
Cohesive soils Short distances Above water table Need steel casing Minor steering
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60-inch Diameter SBU-A
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Pilot Tube Method
Medium distances
Straight alignments with goodaccuracy Variety of soils Smaller shafts Moderate
equipment costs
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Step 1
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Step 2
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Pilot Tube + Plus
Now used as a guide forother method Auger boring Pipe Ramming
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Pipe Ramming Wide range of
diameters Soils only Continuously
supported Typically < 300
Above and belowwater table
Need steel casing
No steering control
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Installation Method Ramming in continuous length or segments
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Rammingin
Progress
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Pilot tube
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Pipe Jacking Large diameters Soils and mixed
ground Face supported Long distances
Above the watertable
Steerable
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Microtunneling Range of diameters (> 12) All ground types
Continuous face support Long distances Above or below water table
Range of pipe materials Steerable to line and grade
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Micro vs Utility TunnelingRemotely operatedPrecise guidancePipes jacked from launch pitContinuous support to face
ConventionalRib & Lagging Tunnel
Microtunnel
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Tunnel Shield Construction
Lining is built within shield. Lining does notmove longitudinally after placement.
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Required Axial Thrust versus Lengthof Drive for Same Diameter
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Opposite Approaches
Open Cut
What happenshappens
Trenchless
Understand and plan
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What to Do? Understand the site history and
potential obstructions
Look at old aerial photos Conduct ageotechnicalprogram
Locate allutilities
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Potential Obstructions
Cobbles or Boulders
Wood Fill materials Hard zones Mixed faces
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Typical Machine Sizes Piercing 2 to 3 inches Pilot Tube 6 to 36 inches
HDD 6 to 54 inches Auger Boring 10 to 60 inches
Pipe Jacking/MT 12 to 96 inches Pipe Ramming 12 to 144 inches Shield 60 to 144 inches
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Typical CMP Culverts
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Replacement Issues
Need to increase size foraquatic passage
Must keep existing culvertactive during construction
Minimize costs Develop the best cross section Use the right materials
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Possible Solutions
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Consume the Culvert
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Use Liner Plate Tunnel
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Closing Thoughts
Methods still evolving Many hybrid methods emerging Better alignment control
emerging in auger boring
applications Must identify potential
obstructions (or get X-ray vision)
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HORIZONTAL DIRECTIONALDRILLING (HDD)
Samuel T. Ariaratnam, PhD, PE
Arizona State University
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BackgroundLengths up to 8,400 feet
Diameters of 2 54
Applications:Utility conduitsPipelinesGravity sewers
Force mainsHorizontal remediation wellsGeotechnical investigations
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Pilot Bore and Tracking
Pilot Bore
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Drill Bits
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Reaming/Hole Enlargement
Reaming
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CLAY
ANNULAR SPACE REGION
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SAND
ANNULAR SPACE REGION
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Pipe Material Distribution
Underground Construction Magazine
9th
Annual Survey, June 2007
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Conclusions HDD is a minimally-intrusive trenchlessconstruction method suited for highly
congested urban areas and high traffic zones Horizontal Directional Drilling equipment is
capable of installing a wide range of utilities HDD will never replace traditional open-cut
methods; however, they complement eachother
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PIPE BURSTING
Samuel T. Ariaratnam, Ph.D., P.E.
Arizona State University
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Pipe Bursting
Lengths typically 300-600 ft
Diameters up to 42
Applications: replacement of force mains
replacement of gravitysewers
Static Head
Pneumatic Head
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Introduction
Emerging field of pipe replacement
Replacement of the host pipe byfragmenting the existing conduitand installing a completely newpipe of equal diameter or larger inits place.
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Applications
Total pipe replacementTypical upsize as much as 20 30%Industrial & Municipal - Main Line &LateralsVarious host and product pipe materialsContinuous or Sectional pipe installation
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Pipe Bursting Feasibility
May achieve lower costs compared
to open trenchLess construction timeMinimal excavationSocial cost savingsReduces ground settlementLow environmental impact
S i M h d (C i )
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Static Method (Continuous)
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Static Method (Sectional)
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Pneumatic Method
Almost all types of pipe can
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Almost all types of pipe canbe burst
Cast iron Steel Ductile iron High Density Polyethylene Polyvinylchloride
Concrete Reinforced concrete Asbestos cement Clay
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VariousHostMaterials
STEEL
CAST IRON
VITRIFIED CLAY
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350mm(14)
750mm
(30)
650mm(26)
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Conclusions Pipe bursting is the only trenchless
method capable of installing a new pipe ofequal or larger diameter as a replacement
option Almost any type of existing pipe can be
burst and replaced with most pipe
materials Proper planning is critical to project
success!
CONTRACTOR QUALIFICATIONS &
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CONTRACTOR QUALIFICATIONS &PRE-QUALIFICATION
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f l
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Protection of Existing Utilities
Call in Locates Obtain As-Built Maps (Shared Responsibility) Mark Utilities (Utility Owners)
Confirm Utilities (Pothole) (Excavator) Protect (Excavator)
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As-Builts, Operator Logs, Notes
Contractor is responsible for marking theplans to indicate any and all vertical andhorizontal deviations between the design
and actual installation Operator logs/notes should be maintainedand updated daily by the Contractor andshould include Pipe number, depth, pitch, steering
commands, and notes
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Damage Avoidance
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Trenchless Training Courses
Horizontal Directional Drilling GoodPractices
Pipe Bursting Good Practices New Installation Methods Good Practices Cured-in-Place Pipe (CIPP) Good
Practices Sewer Laterals Rehabilitation &
Replacement(www.nastt.org)
C lt I t T i i g
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Caltrans Inspector Training
Classroom
Field Exercises
Conclusions
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Conclusions
Well-written specificationsare important to minimizeclaims
Hiring a competentcontractor can be achievedthrough pre-qualification
There are numerousavailable trenchlesstechnology options