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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