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Introduction to Trenchless Methods Presented by Glenn M. Boyce, PhD, PE Senior Associates Presented by Glenn M. Boyce, PhD, PE Senior Associates April.

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Presentation on theme: "Introduction to Trenchless Methods Presented by Glenn M. Boyce, PhD, PE Senior Associates Presented by Glenn M. Boyce, PhD, PE Senior Associates April."— Presentation transcript:

1 Introduction to Trenchless Methods Presented by Glenn M. Boyce, PhD, PE Senior Associates Presented by Glenn M. Boyce, PhD, PE Senior Associates April 21, 2009

2 Presentation Objectives Provide a better understanding of trenchless methods used for new installations Learn the advantages and limitations of the methods Discuss contractor qualifications

3 Types of Infrastructure Gas – Pressure Water – Pressure Sewer – Gravity Drainage – Gravity Power – Non-gravity Communications – Non-gravity

4 Trenchless Methods Impact moling Pipe ramming Auger boring Pilot tube Pipe jacking / Microtunneling Conventional tunneling Horizontal directional drilling Pipe bursting

5 Generic Size and Length MethodSizeLength Moling2” - 12” 150’ Ramming8” - 72” 300’ Auger Bore8” - 60” 250’ Pilot Tube6” - 42” 300’ Microtunneling12” - 108” 1,500’ Pipe Jacking>54” 3,000’ HDD2” - 48” 6,500’ Tunneling>60”Any length

6 What to Do? Choose the right method Use established “Standards” Collect information/investigate Plan ahead Conduct risk assessments Include mechanisms to handle conflicts

7 Use the Right Method Open cut Horizontal Directional Drilling Auger boring Pipe ramming Pipe jacking Microtunneling Tunneling 1996 Pilot Tube

8 Auger Boring Road crossings Cohesive soils Short distances Above water table Need steel casing Minor steering

9 60-inch Diameter SBU-A

10 Pilot Tube Method Medium distances Straight alignments with good accuracy Variety of soils Smaller shafts Moderate equipment costs

11 Step 1




15 Step 2

16 Pilot Tube + “Plus” Now used as a guide for other method – Auger boring – Pipe Ramming

17 Pipe Ramming Wide range of diameters Soils only Continuously supported Typically < 300’ Above and below water table Need steel casing No steering control

18 Installation Method Ramming in continuous length or segments

19 Ramming in Progress

20 Pilot tube

21 Pipe Jacking Large diameters Soils and mixed ground Face supported Long distances Above the water table Steerable

22 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

23 Micro vs Utility Tunneling Remotely operated Precise guidance Pipes jacked from launch pit Continuous support to face Conventional Rib & Lagging Tunnel Microtunnel

24 Tunnel Shield Construction Lining is built within shield. Lining does not move longitudinally after placement.

25 Required Axial Thrust versus Length of Drive for Same Diameter

26 Opposite Approaches Open Cut What happens happens Trenchless Understand and plan

27 What to Do? Understand the site history and potential obstructions Look at old aerial photos Conduct a geotechnical program Locate all utilities

28 Potential Obstructions Cobbles or Boulders Wood Fill materials Hard zones Mixed faces

29 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

30 Typical CMP Culverts

31 Replacement Issues Need to increase size for aquatic passage Must keep existing culvert active during construction Minimize costs Develop the best cross section Use the right materials

32 Possible Solutions

33 Consume the Culvert

34 Use Liner Plate Tunnel

35 Design Solutions Built a parallel pipe barrel – Increases capacity – Allow the existing to remain in service – Get to use the materials you want Slipline the existing after new Built a new entry and exit apron

36 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)

37 HORIZONTAL DIRECTIONAL DRILLING (HDD) Samuel T. Ariaratnam, PhD, PE Arizona State University

38 Background Lengths up to 8,400 feet Lengths up to 8,400 feet Diameters of 2” – 54” Diameters of 2” – 54” Applications: Applications:  Utility conduits  Pipelines  Gravity sewers  Force mains  Horizontal remediation wells  Geotechnical investigations

39 Pilot Bore and Tracking Pilot Bore


41 Drill Bits


43 Reaming/Hole Enlargement Reaming

44 Reamers



47 Pipe Material Distribution Underground Construction Magazine 9 th Annual Survey, June 2007












59 Conclusions HDD is a minimally-intrusive trenchless construction 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 each other

60 PIPE BURSTING Samuel T. Ariaratnam, Ph.D., P.E. Arizona State University

61 Pipe Bursting Lengths typically ft Lengths typically ft Diameters up to 42” Diameters up to 42” Applications: Applications: – replacement of force mains – replacement of gravity sewers Static Head Pneumatic Head

62 Pneumatic Systems - Usually include a pneumatic tool and winch and bursts the pipe using the kinetic energy of the tool. The pipe is usually attached to either the burst head or tool. Static Systems – Usually include a hydraulic power source and a rod shuttling system and use high tonnage to pull new line into place. Small Portable Systems - Either pneumatic or static for doing small diameter and short runs (e.g. laterals). Common Types of Bursting Systems

63 Introduction  Emerging field of pipe replacement  “Replacement of the host pipe by fragmenting the existing conduit and installing a completely new pipe of equal diameter or larger in its place.”

64 Applications  Total pipe replacement  Typical upsize as much as 20 – 30%  Industrial & Municipal - Main Line & Laterals  Various host and product pipe materials  Continuous or Sectional pipe installation

65 Pipe Bursting Feasibility  May achieve lower costs compared to open trench  Less construction time  Minimal excavation  Social cost savings  Reduces ground settlement  Low environmental impact

66 Static Method (Continuous)

67 Static Method (Sectional)

68 Pneumatic Method

69 Almost all types of pipe can be burst … Cast iron Steel Ductile iron High Density Polyethylene Polyvinylchloride Concrete Reinforced concrete Asbestos cement Clay


71 350mm(14”) 750mm(30”) 650mm(26”)

72 Conclusions Pipe bursting is the only trenchless method capable of installing a new pipe of equal 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!


74 Introduction The majority of trenchless contractors are reliable and follow good installation practices However, agencies must be aware of those few “cowboy” contractors Qualifying contractors is a recommended practice for trenchless projects to ensure use of competent contractors

75 Specifications Manufacturers Recommended Specifications Industry/Association Specification Guidelines Project Specific

76 Testing & Inspection  Quality Assurance & Controls in Specifications  Trained Inspectors  Testing by Owner Laboratory  Final CCTV Inspection of the Installed Pipe

77 Protection of Existing Utilities Call in Locates Obtain As-Built Maps (Shared Responsibility) Mark Utilities (Utility Owners) Confirm Utilities (Pothole) (Excavator) Protect (Excavator)

78 Protection of Existing Utilities – Locate Marks

79 As-Builts, Operator Logs, Notes Contractor is responsible for marking the plans to indicate any and all vertical and horizontal deviations between the design and actual installation Operator logs/notes should be maintained and updated daily by the Contractor and should include –Pipe number, depth, pitch, steering commands, and notes

80 Logbook/Field Notes

81 Contractor Submittals Proof of success on prior similar projects Pipe material, diameter, length Make/model of equipment, guidance equipment, fluid mixture Slurry disposal plan Contingency plan Safe plan and protocols Certification by the manufacturer that the Contractor’s personnel are trained in the use of the equipment Training certification for pipe installation Fusion training certification for HDPE Construction Plan & Installation Schedule Traffic Control Plan

82 Damage Avoidance

83 Trenchless Training Courses Horizontal Directional Drilling Good Practices Pipe Bursting Good Practices New Installation Methods Good Practices Cured-in-Place Pipe (CIPP) Good Practices Sewer Laterals Rehabilitation & Replacement (

84 Caltrans Inspector Training Classroom Field Exercises

85 Conclusions Well-written specifications are important to minimize claims Hiring a competent contractor can be achieved through pre-qualification There are numerous available trenchless technology options

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