No Dig TechnologyNo Dig Technology

Introduction: Introduction: Introduction: Introduction: No-Dig Technology is the art and science ofinstalling repairing or renewing undergroundinstalling, repairing or renewing undergroundpipes, ducts and cables using techniques thatminimizes / eliminates the need for excavation,i t ti d th f b fi.e., constructing under the surface or subsurfaceconstruction.The term trenchless technology has been in usegyon a global basis since the mid-1970s (Japan).The use of such techniques can reduceenvironmental impact, social costs and at theenvironmental impact, social costs and at thesame time provide economic alternatives totraditional open cut methods of installation,renewal or repairrenewal or repair.

No Dig Technology… why adopt?No Dig Technology… why adopt?No Dig Technology… why adopt?No Dig Technology… why adopt?Faster schedules can be achieved since time required for diversionof utilities traffic etc are avoided Works for installation of sewerof utilities, traffic etc are avoided. Works for installation of sewerpipes can carry on regardless of state of traffic at the ground level.Less relocation of utilities is required and risk of damage to utilitiesis reducedis reduced.Risk of damage to existing structures is reduced as pavements,roads, trees do not have to be excavated or cut.Surface settlement is minimized resulting in less damage tosurrounding buildings and structures.No lowering of groundwater table is required.Existing commercial activities at ground surface can carry onunabated.Amount of earth moved is reduced, leading to lower disposal costs., g pReduced risks to workers due to absence of temporary structuresand earth collapse.

Types of Pipes:Types of Pipes:Types of Pipes:Types of Pipes:All types of rigid or flexible pipes can be burst/ installed/

i d irepaired, viz:Clay Steel Polymer Ductile Iron Polyethylene CementConcreteConcreteHobas (Fibre glass) Poly Vinyl Chloride (PVC) HighDensity Polyethylene (HDPE)

ApplicationApplication::ApplicationApplication::Gas Lines, Water Lines, Sewer Mains, CommunicationDucts/Cables

Investigations:Investigations:Investigations:Investigations:Site investigation to determine soil andgroundwater conditionsInspection to determine the condition of thepipelineLocation survey to determine the position of

i ti i li th i d t ti lexisting pipelines, other services and potentialobstaclesNo Dig Technology is concerned largely withNo-Dig Technology is concerned largely withservices too small to permit man entry, generallyup to about 900mm diameter pipes and ducts.up to about 900mm diameter pipes and ducts.

Site Investigation:Site Investigation:Site Investigation:Site Investigation:For providing service it is important that adequate andd il d i i i i i h l i l idetailed site investigation with relevant material testingbe carried out and that the information and itsinterpretations are made available.p

Condition Survey:Condition Survey:Condition Survey:Condition Survey:This survey is carried out when there is doubt

i h di i f i i d dconcerning the condition of an existing undergroundnetwork. It is important to carry out a CCTV survey.

Underground Detection:Underground Detection:Underground Detection:Underground Detection:In No-Dig method the position of the driving tool is

i l i d i i i hcontinuously monitored using a transmitter in thedriving head and a locater on the surface.

NoNo--Dig Systems:Dig Systems:NoNo Dig Systems:Dig Systems:Trenchless Technology Systems forunderground utility services fall into three broadcategories:

Installation of a new pipeline or duct;On line replacement of an existing pipeline or duct; R i /R i f i i i liRenovation/Repair of an existing pipeline or duct.

New Installations:New Installations:New Installations:New Installations:The methods for the installation of a newpipeline or duct along with service connectionsare:

Micro Tunneling Short Drive Systems Horizontal Directional Drilling Guided Drilling

Micro TunnelingMicro TunnelingMicro Tunneling…Micro Tunneling…Controlled Excavation Steerable - less than 1000mmdiameterdiameter

MTBM’s have now been developed to work from driveshafts in almost all types of ground conditionsshafts in almost all types of ground conditions.Micro tunneling is used extensively for sewerage workwhere surface disruption has to be minimized. Itprovides the necessary degree of accuracy in gravityprovides the necessary degree of accuracy in gravitylines.With the development of micro tunneling, both concreteand clay pipes have been designed with jacking in mindand clay pipes have been designed with jacking in mind.Pipes in all conventional materials are produced with in-wall joints and in shorter lengths to enable smaller driveshafts to be used, thus reducing excavation volumes andgroad occupancy.

Micro TunnelingMicro Tunneling…Micro Tunneling…Micro Tunneling

Schematics courtesy of ISTT

Short Drive SystemsShort Drive SystemsShort Drive Systems…Short Drive Systems…Essentially Un Steered - Soil DisplacementA B i & Th B iAuger Boring & Thrust BoringAuger Boring utilizes a rotating head to excavate the soil which istransported by auger flights operating in a casing to the drive pit.

h h d i d i i i h h f hThe head is recovered at an exit pit or in the trench cut for theadjacent length of pipeline. Auger boring is used in the range of 100- 1000mm diameter.

Short Drive SystemsShort Drive Systems…Short Drive Systems……Short Drive Systems…Impact Moling

Impact moling is a technique in which a percussive mole (soildisplacement hammer) is launched from an excavation todisplace the soil and form a bore. The new conduit isnormally drawn in behind the mole or pulled back into thebore using the hammers reverse action. Pneumatically drivenmoles, in which the soil is displaced by the action of apercussive piston have been developed in the range 30 -percussive piston, have been developed in the range 30180mm diameter for a single operation, with repetitivemultiple passes to achieve 200 - 250mm diameter.

They are used to install services for all utilities. Moles arecommonly used by gas and water undertakings forinstallations of up to 40m under roads, drives and gardens inmaking 45 65mm diameter house connectionsmaking 45-65mm diameter house connections.

Short Drive SystemsShort Drive Systems…Short Drive Systems……Short Drive Systems…Pipe Ramming/ Thrust BoringAre processes where a casing, usually steel, is driven through theground from the drive pit to the exit pit. In Pipe Ramming, thecasing is driven by a pneumatic hammer whilst in Thrust Boring iti d d b i h h d li his advanced by a straight hydraulic push.Rams of pipes up to and over 2m diameter and exceeding 70m inlength have been achieved.

Horizontal Directional DrillingHorizontal Directional DrillingHorizontal Directional DrillingHorizontal Directional DrillingSteerable Heavy, powerful rig - large size range - Long distancesThi i i ll d l d b h il i d f iThis system was originally developed by the oil industry for rivercrossings of small diameter where no high degree of accuracy wasrequired. They are now widely used for installing pressure pipesunder major obstacles such as motorway intersections large riversunder major obstacles such as motorway intersections, large riversand airport runways.

Guided DrillingGuided DrillingGuided DrillingGuided DrillingSteerable Small Rig - Shallow Drilling - MediumL thLengthGuided drilling employs an excavation withcompact light weight rig for rapid mobilizationcompact light weight rig for rapid mobilization.Small diameter jets, mechanized cutting tools ordisplacement heads attached to a flexible drillt i iti d t f b th h d istring are positioned to form a bore as the head is

thrust forward. The drilling head is launched fromthe surface at an inclined angle. Steering, in bothg gvertical and horizontal planes, is effected bycontrolling the orientation of a slant face at theheadhead.

OnOn--Line Replacement:Line Replacement:OnOn Line Replacement:Line Replacement:

Methods of on-line replacement are: p

Pipe burstingPipe bursting Pipe Eating

Pipe BurstingPipe BurstingPipe Bursting…Pipe Bursting…New for Old without Trenching - Size for Size &Upsize CapableUpsize CapableIn this method old pipes are replaced byfragmenting the pipe of equal or larger diameterpipepipe.Pipe Bursting, sometimes called Pipe Splitting (usedon non-fragmental pipes such as Steel, Ductile Iron

P l th l ) d h b d l d t l itor Polyethylene), and has been developed to exploitthis resource. Initially the aim was for size-for-sizereplacement by splitting the defective pipe anddi l i th f t t bl i li fdisplacing the fragments to enable a new pipeline ofthe same diameter, usually of polyethylene (PE), tobe drawn in.

Pipe BurstingPipe Bursting…Pipe Bursting……Pipe Bursting…It is used for replacement of fractured pipeusually from excavations 10-200m apart.Upsizing from 100mm to 225mm diameter is

ll t bli h d d i f t 600now well established, and pipes of up to 600mmdiameter and greater have been replaced.

Pipe BurstingPipe Bursting…Pipe Bursting…Pipe BurstingTwo methods are commonly used as outlined:Static Bursting (Rod or Winch Systems) &Pneumatic Bursting

Pipe EatingPipe EatingPipe EatingPipe EatingNew for Old without Trenching - Enlargement -S blSteerablePipe Eating is an on-line micro tunneled replacementtechnique. The existing defective pipeline is crushed andtechnique. The existing defective pipeline is crushed andremoved through the new pipeline by the circulatingslurry system. A new pipe is simultaneously installed byj ki b hi d th i t li hijacking behind the micro tunneling machine.

Renovation Renovation Renovation Renovation

Renovation methods are:

Slip liningSlip lining Lining Formed in Place S O Li iSpray-On Lining Localized Repair Chemical Stabilization

Sliplining Sliplining Sliplining …Sliplining …New for Old without Trenching - Long Lengths

It is one of the earliest forms of continuous structurallining. A new pipeline of smaller diameter is insertedg p pinto the defective pipe and the annulus grouted. It issimple and is relatively inexpensive. However, there canbe significant loss of hydraulic capacity.g y p y

Examples include the pulling in of long lengths of PEpipes within water mains or the insertion of individualpipes within water mains or the insertion of individualpipes within sewers. This is generally a low costtechnique, which has the disadvantage of reduction ofborebore.

SlipliningSliplining…Sliplining…Sliplining

Epoxy Spraylining System / CIPPEpoxy Spraylining System / CIPPEpoxy Spraylining System / CIPPEpoxy Spraylining System / CIPPThese are methods of lining pipes with a thin lining of

i ( i ll 1 hi k) hi h i d hresin (typically 1mm thick), which is sprayed onto thesurface of a cleaned main. The aim of these techniquesis to isolate the host pipe from the conveyed medium.p p yThere may be some potential for these techniques to beused to reinforce the structural capabilities of the hostmainmain.

Spray On LiningSpray On LiningSpray On LiningSpray On LiningCorrosion ProtectionThis is a well tried and tested technique for applyingeither anti-corrosion or structural lining to pipes. A highspeed rotating head is winched through the pipeline,speed rotating head is winched through the pipeline,centrifugally depositing the lining material over the fullinternal surface.

Localised RepairLocalised RepairLocalised RepairLocalised RepairResin Injection and Chemical Grouting atTrouble SpotsTrouble SpotsLocal defects may be found in an otherwisesound pipeline, due to cracking or joint failure.Systems are available for remote control resininjection to seal localized defects in the range100mm - 600mm diameter.Chemical Grouting with urethane and similarmaterials has been used for many years in sewerrehabilitation Remote and man-entry groutingrehabilitation. Remote and man-entry groutingof defective joints and cracks may preventinfiltration and the formation of external voidsin an otherwise sound pipelinein an otherwise sound pipeline.

Chemical StabilizationChemical StabilizationChemical StabilizationChemical StabilizationRestoring Support for SewersThe stability of sewers in doubtful ground conditions may berestored by treating manhole lengths with a two-part chemicaldosing. The sewer length is sealed and filled first with solution A

hi h i h d d fill d i h l i B hi h i lwhich is then pumped out and refilled with solution B which is alsosubsequently pumped out. The chemical reaction between thecomponents seals joints and cracks in the pipe and stabilises thesurrounding soilsurrounding soil.