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Directional BoringDirectional Boring{{

Directional BoringDirectional BoringAn Introduction to the HDD ProcessAn Introduction to the HDD Process{{

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Presentation ObjectivesPresentation Objectives Provide a description of how DirectionalProvide a description of how Directional

Presentation ObjectivesPresentation Objectives Provide a description of how Directional Provide a description of how Directional Boring worksBoring works

CC h b f l lh b f l l Cover Cover the basics for planning a Directional the basics for planning a Directional BoreBore

Discuss the advantages & limitations of Discuss the advantages & limitations of Directional BoringDirectional Boring


What is Directional Boring?What is Directional Boring?gg

A method for installing pipe underground without A method for installing pipe underground without g p p gg p p gtrenching, where the equipment is able to be guided trenching, where the equipment is able to be guided below or around obstaclesbelow or around obstacles


Process:Process: Step 1Step 1 the Pilot Borethe Pilot BoreProcess: Process: Step 1 Step 1 ‐‐ the Pilot Borethe Pilot Bore

A pilot hole is drilled beginning at an A pilot hole is drilled beginning at an adjustable angle relative to the surface which adjustable angle relative to the surface which continues under and across the obstacle alongcontinues under and across the obstacle alongcontinues under and across the obstacle along continues under and across the obstacle along the designed profilethe designed profile


Step 1: Step 1: Directional ControlDirectional Controlpp

The directional control is brought about by a varied bevel The directional control is brought about by a varied bevel on the drill head. on the drill head.

Apply force with out rotation to change directionApply force with out rotation to change direction

Apply force with Apply force with rotation rotation to to continue on the same trajectorycontinue on the same trajectory


Step 1: Step 1: Electronic GuidanceElectronic Guidancepp

Information about the roll, pitch & depth of the drill housing Information about the roll, pitch & depth of the drill housing underground is communicated using a radio frequency tracking underground is communicated using a radio frequency tracking system. system. yy

Commonly referred to as a “walkover” locating system, since a Commonly referred to as a “walkover” locating system, since a locator needs to walk locator needs to walk with the progression with the progression of the drill of the drill housing along housing along the bore paththe bore path


Process:Process: Step 2Step 2 thethe PrereamPrereamProcess: Process: Step 2 Step 2 ‐‐ the the PrereamPreream

The bore hole may need to be enlarged to a The bore hole may need to be enlarged to a greater diameter depending on what size pipe or greater diameter depending on what size pipe or how many pipes are being installedhow many pipes are being installedhow many pipes are being installedhow many pipes are being installed

The process of successively increasing the The process of successively increasing the diameter of the bore hole is called “prereaming”diameter of the bore hole is called “prereaming”


Step 2: Step 2: ReamersReamerspp

Reamer designs vary greatly for different soil conditionsReamer designs vary greatly for different soil conditions

Often, you may use a combination of reamer sizes and Often, you may use a combination of reamer sizes and designs to not only cut the bore, but clean the bore hole of designs to not only cut the bore, but clean the bore hole of solid material and also stabilize the bore holesolid material and also stabilize the bore hole


Process:Process: Step 3Step 3 the Pullbackthe PullbackProcess: Process: Step 3 Step 3 ‐‐ the Pullbackthe Pullback

Once the bore hole is enlarged to the proper Once the bore hole is enlarged to the proper diameterdiameterC t t th i d t d “P llb k” tC t t th i d t d “P llb k” t Connect to the pipe product and “Pullback” to Connect to the pipe product and “Pullback” to the bore machinethe bore machine


Step 3: Step 3: Pullback ToolingPullback Toolingpp

The reamer continues to cut material during the pullback to The reamer continues to cut material during the pullback to reduce pullback pressurereduce pullback pressure

A swivel is introduced between the reamer and the pipe to A swivel is introduced between the reamer and the pipe to p pp peliminate rotational binding eliminate rotational binding downholedownhole during pullbackduring pullback

A mud tight pipe puller is connected to the pipe to ensure no A mud tight pipe puller is connected to the pipe to ensure no drilling mud enters the pipe during pullbackdrilling mud enters the pipe during pullbackg p p g pg p p g p


Process:Process: Full Sequence AnimationFull Sequence AnimationProcess: Process: Full Sequence AnimationFull Sequence Animation


Typical Pipe Materials for HDDTypical Pipe Materials for HDDHDPE Pipe Boregard Pipe (PVC sch40)

Picking the appropriate pipe material for a directional bore is a very Picking the appropriate pipe material for a directional bore is a very important part of setting up a successful installationimportant part of setting up a successful installationimportant part of setting up a successful installationimportant part of setting up a successful installation

Not every pipe material makes sense for every directional boring Not every pipe material makes sense for every directional boring application application


The Byproduct of Directional BoringThe Byproduct of Directional Boring

Directional Boring’s main byproduct the “bore mud” or “returns” that Directional Boring’s main byproduct the “bore mud” or “returns” that flows back to your entry & exit pits during the process. flows back to your entry & exit pits during the process. Bore Mud is in large part the spoils from the hori ontal hole you areBore Mud is in large part the spoils from the hori ontal hole you are Bore Mud is in large part the spoils from the horizontal hole you are Bore Mud is in large part the spoils from the horizontal hole you are cutting to place your pipes.cutting to place your pipes.

The disposal cost of bore mud remains one of the main costs for the The disposal cost of bore mud remains one of the main costs for the Directional Boring processDirectional Boring process


Compaction around the Directional BoreCompaction around the Directional Bore

Sand Clay

A study has conducted by Arizona State University to confirm A study has conducted by Arizona State University to confirm compaction around pipes that have been installed by directional borecompaction around pipes that have been installed by directional boreThese photos represent directional bores that ha e been in the ground forThese photos represent directional bores that ha e been in the ground for These photos represent directional bores that have been in the ground for These photos represent directional bores that have been in the ground for 6 months and have no annular space around the pipes6 months and have no annular space around the pipes


Setting up a Directional BoreSetting up a Directional Bore

Various factors contribute to determining if directional Various factors contribute to determining if directional ggboring is feasible for a specific site: boring is feasible for a specific site:


Determining Setup SpaceDetermining Setup Space Does the site have an Does the site have an

access point the access point the equipment can fit in?equipment can fit in?

When setting up a When setting up a directional bore you directional bore you must:must: Determine setup Determine setup

space required for space required for the drill rigthe drill riggg

Determine laydown Determine laydown area behind the exit area behind the exit pit for pulling the pit for pulling the pipe backpipe backpipe backpipe back

Determine drilling Determine drilling safe “window” from safe “window” from existing utilitiesexisting utilities


Protection of Existing UtilitiesProtection of Existing Utilities

Call in USA LocatesCall in USA Locates

Obtain AsObtain As‐‐Built Maps prior to mobilizationBuilt Maps prior to mobilization Use secondary utility locator in private propertyUse secondary utility locator in private property Use secondary utility locator in private propertyUse secondary utility locator in private property Confirm size & depth of all existing utilities by potholingConfirm size & depth of all existing utilities by potholing Record: size, depth, & locationRecord: size, depth, & location


Determine Bore ProfileDetermine Bore Profile

After the depth After the depth of all existing of all existing utilities have utilities have been locatedbeen locatedA f d illiA f d illiA safe drilling A safe drilling “window” can be “window” can be established. established.


Bore Profile DocumentationBore Profile Documentation Every General Contractor/Owner Every General Contractor/Owner

that implements directional boring that implements directional boring needs to receive an accurate bore needs to receive an accurate bore profile or “Borelog”.profile or “Borelog”.

A Borelog is a record of the depth A Borelog is a record of the depth the directional bore has drilled toothe directional bore has drilled toothe directional bore has drilled too the directional bore has drilled too for each full rod in the directional for each full rod in the directional boring machineboring machine

Thi e o d ould the beThi e o d ould the be This record could then be This record could then be converted to a profile for Asconverted to a profile for As‐‐Built Built records.records.


Cost DeterminersCost Determiners There are a few major cost There are a few major cost

determiners in with determiners in with directional boringdirectional boring

Amount of setupsAmount of setups Amount of setupsAmount of setups Multiple setups can Multiple setups can

add considerable time add considerable time to a projectto a project

Length of boresLength of bores Length of boresLength of bores Bores in excess of 500’ Bores in excess of 500’

can require additional can require additional preparation, preparation, increasing costincreasing costgg

Amount of conduits in Amount of conduits in each boreeach bore Diameter of bore Diameter of bore

increases addingincreases addingincreases adding increases adding “prereaming” to the “prereaming” to the sequence & added sequence & added mud disposal mud disposal


Design Ideas to Lower CostsDesign Ideas to Lower Costs


Directional Boring LimitationsDirectional Boring Limitations Soil conditions/length of pipe drivesSoil conditions/length of pipe drives

Directional Boring LimitationsDirectional Boring Limitations Soil conditions/length of pipe drives Soil conditions/length of pipe drives equipment selectionequipment selection

N tN t it bl f ll itit bl f ll it Not Not suitable for small sites suitable for small sites

Dense Dense utility areas complicate obtaining a utility areas complicate obtaining a y p gy p g“window”“window”

ConcreteConcrete encasementencasement Concrete Concrete encasementencasement


Directional Boring AdvantagesDirectional Boring Advantages

Mi i l di i iMi i l di i i

Directional Boring AdvantagesDirectional Boring Advantages

Minimal disruption to environmentMinimal disruption to environment Minimal restoration neededMinimal restoration needed Permits are easier to obtainedPermits are easier to obtained Minimize traffic controlMinimize traffic control Cost reductionCost reduction

A hi d th f f tA hi d th f f t Achieve depth of cover fasterAchieve depth of cover faster Suitable for a variety of soil conditionsSuitable for a variety of soil conditions Safer construction methods for workersSafer construction methods for workers


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