HDD-Practice Handbook

H.-J. Bayer (Hrsg.)

HDD-Practice Handbook

Vulkan-Verlag · Essen · Germany

3

Table of contents

Preface ................................................................................................ 5

1 Introduction ........................................................................................ 13

1.1 Definition of the term HDD .................................................................. 13

1.2 History of drilling and HDD .................................................................. 13

1.3 Fundamental differences between horizontal and vertical drilling technique .............................................................................................. 17

2 Technology of trenchless pipeline installation with HDD .......... 19

2.1 Methodology of drilling control ............................................................ 19

2.2 Methodology of pipeline installation .................................................... 20

2.3 Range of horizontal drilling systems .................................................... 21

2.4 Qualified realisation of trenchless pipe installation projects ................ 222.4.1 Planning phase .................................................................................... 222.4.2 Pipe material control phase .................................................................. 232.4.3 Maschine control phase ........................................................................ 232.4.4 Construction phase .............................................................................. 232.4.5 Reworking phase .................................................................................. 242.5 Suitable pipe materials ........................................................................ 242.6 Advantages of HDD in pipeline installation .......................................... 25

3 Soil analysis as a precondition for successful pipe installation .......................................................................................... 28

3.1 Historical perspective ............................................................................ 28

3.2 Early soil investigation in pipe installation ............................................ 28

3.3 Legal liability for soil conditions ............................................................ 29

3.4 Soil analysis as academic discipline .................................................... 29

3.5 Norms regulating soil analysis and material classification .................. 30

3.6 Investigation criteria for pipe installation .............................................. 30

3.7 The soil: risk and calculation factor ...................................................... 31

3.8 Soil investigation .................................................................................. 31

3.9 Conclusion ............................................................................................ 33

4 Comparison of trenchless and open cut construction .............. 34

4.1 Introduction .......................................................................................... 34

4.2 Comparative examination of construction methods ............................ 344.2.1 Required equipment and number of transport runs ............................ 344.2.2 Required construction time .................................................................. 36

Inhaltsverzeichnis 7

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4.2.3 Affected traffiic areas .......................................................................... 364.2.4 Noise and dirt factors .......................................................................... 364.2.5 Required amount of reinstatement material .......................................... 374.2.6 Resource consumption and corresponding disposal site

requirements ........................................................................................ 374.2.7 Indirect cost .......................................................................................... 384.2.8 Installation effects on street paving and pipe service life .................... 40

5 HDD machine technology .............................................................. 43

5.1 Drilling unit classification ...................................................................... 435.1.1 Shaft bore machines.............................................................................. 435.1.2 Mini bore rigs ........................................................................................ 465.1.3 Midi bore rigs ........................................................................................ 465.1.4 Maxi bore rigs ........................................................................................ 465.1.5 Mega bore rigs ...................................................................................... 465.1.6 Performance limits ................................................................................ 47

5.2 Main components ................................................................................ 475.2.1 Drilling system ...................................................................................... 485.2.1.1 Bore rig ................................................................................................ 485.2.1.2 Slide drill (bore rig, upper part) ............................................................ 485.2.1.3 Undercarriage and stability (bore rig, lower part) ................................ 485.2.1.4 Drive and hydraulic units ...................................................................... 495.2.1.5 Percussive unit ...................................................................................... 495.2.1.6 Safety equipment .................................................................................. 495.2.2 Drilling fluid mixing unit and mud pump .............................................. 505.2.3 Pipe string (drill rods und bore tools) .................................................. 525.2.3.1 Drill rods ................................................................................................ 525.2.3.2 Drill rod magazine .................................................................................. 545.2.4 Bore tools ............................................................................................ 555.2.4.1 Bore heads for pilot bores .................................................................... 555.2.4.2 Upsizing tools (backreamers) .............................................................. 575.2.4.3 Swivels .................................................................................................. 595.2.4.4 Pipe pulling device ................................................................................ 595.2.5 Control and detection technique .......................................................... 605.2.5.1 Detection of the bore head .................................................................. 605.2.5.2 Walkover techniques.............................................................................. 605.2.5.3 Wire-Cable techniques .......................................................................... 615.2.5.4 Operating panel .................................................................................... 625.2.6 Transport and supply units .................................................................. 625.2.7 Recycling unit (optional) ...................................................................... 63

5.3 HDD accessories .................................................................................. 635.3.1 Software for planning, representation and documentation of bores .... 635.3.2 Software for soil testing, defining of the drilling fluid and bore

tooling .................................................................................................... 635.3.3 Software for material and jobsite requirement calculation.................... 645.3.4 Pulling force measure and recording and documentation software .... 65

5.4 Requirements for applying the HDD mega rig technique .................... 655.4.1 Transport .............................................................................................. 65

8 Inhaltsverzeichnis


5.4.2 Jobsite planning and control ................................................................ 665.4.3 Rollers and overbends .......................................................................... 665.4.4 Ballasting .............................................................................................. 67

6 Drilling fluids ...................................................................................... 68

6.1 Drilling fluid functions .......................................................................... 68

6.2 Establishing stable boreholes with the HDD method............................ 686.2.1 Soil expertise ........................................................................................ 696.2.2 Essential basic material: bentonite ...................................................... 696.2.3 Complementary requirements during a bore ........................................ 70

6.3 Frequent dangers to drilled boreholes and their countermeasures ...... 706.3.1 Drilling fluid loss .................................................................................... 706.3.2 Drilling fluid run-off .............................................................................. 726.3.3 Drilling fluid extrusion .......................................................................... 726.3.4 Constriction of a borehole .................................................................... 726.3.5 Borehole collapse in loose rock .......................................................... 746.3.6 Borehole collapse ................................................................................ 75

6.4 Emergency kit ...................................................................................... 76

6.5 Drilling fluid handbook .......................................................................... 77

7 Rock drilling technique with low-flow mud motors .................. 78

7.1 Basic features of mud motors .............................................................. 78

7.2 Applications of mud motors in HDD...................................................... 79

7.3 Mud motor technique .......................................................................... 79

7.4 Performance characteristics ................................................................ 81

7.5 Special features of HDD mud motors.................................................... 83

7.6 HDD mud motors for small boring systems .......................................... 84

8 Application range of HDD .............................................................. 85

8.1 Installation of supply and drainage lines .............................................. 858.1.1 Parallel installations for line networks .................................................. 858.1.2 Pressure drainage ................................................................................ 868.1.3 Data lines and telecommunication cables ............................................ 868.1.4 Data lines for traffic guidance and toll systems .................................... 878.1.5 Signal cables alongside long-distance lines ........................................ 878.1.6 Inner pipe relining ................................................................................ 878.1.7 Crossings, under-crossings and under-river crossings ........................ 888.1.8 Installation in rural conservation and green areas ................................ 898.1.9 Installation in protected ground ............................................................ 898.1.10 Installation of flexible anodes ................................................................ 898.1.11 Additional installation of airport navigation lights ................................ 898.1.12 Underground heating ............................................................................ 908.1.13 Connection service lines to dwellings .................................................. 908.1.14 Building connections in hillsides .......................................................... 918.1.14.1 Connections to new buildings .............................................................. 91

8.1.14.2 Renewal of connections to existing buildings ...................................... 918.1.14.3 Property connections in creeping and sliding hillsides ........................ 928.1.14.4 Short property connections with Pit boring systems .......................... 938.1.14.5 Property connections in rocky ground ................................................ 938.1.14.6 Advantages of trenchless installations in hillside terrain ...................... 94

8.2 Water development, hydraulic measures, environmental technology, and irrigation ........................................................................................ 94

8.2.1 Horizontal drinking water wells ............................................................ 948.2.2 Horizontal wells for lowering ground water levels ................................ 958.2.3 Ground water regulation – ground water elevation .............................. 968.2.4 Hydraulic redevelopment ...................................................................... 968.2.5 Further contamination redevelopment .................................................. 978.2.6 Drainage of moving slopes .................................................................. 978.2.7 Drain ...................................................................................................... 988.2.8 Irrigation ................................................................................................ 988.2.9 Monitoring ............................................................................................ 988.2.10 Sensor lines for leakage detection ...................................................... 99

8.3 Special civil engineering, foundations, tunnelling and geotechnical applications .......................................................................................... 99

8.3.1 Geotechnical investigation .................................................................. 998.3.2 Anchoring .............................................................................................. 998.3.3 Tunnel improvement ............................................................................ 1008.3.4 Bores for ground freezing .................................................................... 1008.3.5 Injections................................................................................................ 1008.3.6 Slope stabilisation ................................................................................ 1018.3.7 Bores for geotechnical instruments ...................................................... 1028.3.8 Bores for load settlement .................................................................... 1028.3.9 Precedent ridge stabilisation ................................................................ 1038.3.10 Fill base sealing .................................................................................... 1048.3.11 Soil improvement .................................................................................. 1048.3.12 Further applications .............................................................................. 105

9 Practical application examples ...................................................... 107

9.1 Installation of a cable duct parallel to a motorway .............................. 108

9.2 Installation of a gas line through Holzhausen ...................................... 109

9.3 Installation of a desalination sea intake pipe in Cyprus ...................... 110

9.4 Installation of a water main under railway tracks ................................ 114

9.5 Installation of a HDPE protection pipe under the river Kinzig .............. 116

9.6 Installation of a large pipe bundle under the river Danube .................. 117

9.7 Undercrossing the upper Rhine at 400 m length and 24 m depth ...... 120

9.8 Installation of a sewage line (800 mm) underneath the River Oka ........ 121

9.9 Rivercrossing through limestone .......................................................... 123

9.10 Installation of several cable ducts in the desert .................................. 124

9.11 Installation of a sewer pipe in the Rhine harbour in Duisburg ............ 127

10 Inhaltsverzeichnis

9.12 Installation of a 450 mm drain pipe into the Baltic Sea ...................... 129

9.13 450 meter bore under an airfield .......................................................... 131

9.14 Undercrossing a dune to install a seawater extraction line ................ 134

9.15 Installation of a lakewater retrieval pipe under Lake Constance ........ 137

9.16 Installation of a drinking water pipe through the mud-flats ................ 140

9.17 Anchoring a railway embankment for the construction of a subwaytunnel .................................................................................................... 143

9.18 Construction of pedestrian tunnels in Abu Dhabi ................................ 146

9.19 Installation of pipelines to a distribution position on Dutch island ...... 148

9.20 House connections with steerable boring technique .......................... 151

9.21 Open slope installation in difficult sorroundings .................................. 154

9.22 Rainwater drain sanitation .................................................................... 158

9.23 Installation of a rainwater sewer pipe ND 560 through rock ................ 163

9.24 Construction a new gas pipeline across the river Rhone .................... 166

9.25 Installation of a 1100 mm ductile cast iron pipeline ND 600 .............. 170

10 Technical guidelines and quality assurance in HDD .................. 178

10.1 DCA, ISTT and GSTT guidelines .......................................................... 178

10.2 Directives and standards ...................................................................... 178

10.3 Guidelines for the practice .................................................................. 179

11 HDD literature .................................................................................... 184

11.1 Publications .......................................................................................... 184

11.2 Documentations by associations, technical rules ................................ 187

11.3 Further information on the Internet / Links............................................ 188

Index of advertisers .......................................................................... 189


HDD-Practice Handbook

1

1 Introduction

1.1 Definition of the term HDDDuring the past few years, an international generic term has been established forsteerable horizontal drilling technique that – originating in the US – has gainedacceptance in nearly every country worldwide: HDD = Horizontal Directional Drilling.

Horizontally steered directional drilling was developed in California in the 1970s andwas introduced in Europe in 1986 by the name of ‘controlled horizontal flush drillingtechnique’. Since the term ”flush drilling technique” was put on a level with ”burying ofpipes” in utility technique, the term was attributed to near-surface steerable horizontaldrilling which provides a more functional description of the process.

Contrary to ”deep and deflected horizontal drilling” that has in the meantime becomethe term most commonly used in the oil and natural gas industries, this term as well asthe international abbreviation of HDD are defined as near-surface installation of pipes,cables, filtering wells, oblong structures and devices, holding systems and others usingmobile drilling installations with tilted bore rigs, with three-dimensional detection andcontrol functions, with integrated flush drilling technique and the possibility to upsizecreated boreholes at random, preferably in reverse mode.

1.2 History of drilling and HDDAround 600 B.C. In China about 500 m deep vertical bores are possible

Around 1420 B.C. First proof of vertical drilling technique in Europe

Before 1495 Leonardo da Vinci invents and constructs the first horizontal drillingmachine above ground. It serves to bore wooden logs to producewooden water pipes. In his lifetime, ten horizontal drilling machinesare presumed to have been built (Figure 1.1). Leonardo da Vincialso improves the mechanism of vertical drilling.

Around 1780 Vertical bores up to 300 m deep can be sunk

Around 1850 Wrought iron drill stems, steam engines and diamond bore headsopen up new possibilities for drilling

1860 – 1890 Important inventions in vertical drilling achieved a depth of 2000 maround 1890

Around 1910 First roller chisel (toothed roller chisel)

Around 1920 First underground horizontal drilling machines to siphon off lightcarburetted hydrogen gas (methane) from coal beds of the Ruhrdistrict (machines built by company in Sprockhövel/ southern Ruhrdistrict)

Around 1920 Diesel and Otto engines, electric motors and compressed-airmotors, drilling turbines, impregnated diamond-boring toolsbecome available

1938 Depth of 4500 m is reached

1958 Vertical depth of 7700 m is reached

Introduction 13

1962 Field test of first screw type motors (mud motors)

1972 Vertical depth of 9160 m reached

1972 First horizontal bore below Pajara River near Watsonville inCalifornia by Martin Cherrington using a tilted vertical directionaldrilling unit

1972 – 1979 Martin Cherrington and others achieved 36 crossings under riversand traffic routes

1979 Construction of ”original form” of horizontal bore unit for near-surface use with flat slanted bore rig for installing pipelines

Around 1980 Start of data collection in drilling technique

1982 –1985 Former Boeing aircraft engineers together with scientists of EPRI(US electric power research institute) develop the boring/cuttingground cut using jets. As a result (made by FlowMole), small HDDunits for the installation of 1 kV power cables are developed. Theunits are equipped with (aircraft) intensifiers to create high pressurefor washing, an integrated transmitter-receiver detection technique,highly flexible bore stems and asymmetrical bore heads as well asobtuse, graded reamers.

14 Introduction

Figure 1.1: Horizontal directional drilling machine, designed and drawn by Leonardo da Vinci

1983 – 85 The US Gas Research Institute, Chicago and Charles MachineWorks (Ditch Witch) develop a dry horizontal bore unit with positiondetection. A hydraulic drill rig is combined with a bevelled soildisplacement hammer (pneumatic rocket) on a hollow bore stem. Along inclined steering surface on the bore head characterises thedry bore units that years later also work with drilling fluid.

1985 13000 m are reached using deep drilling technique

1986 The first bore in Europe using HDD is carried out on the premisesof Karlsruhe research centre. FlowTex as a licensee of FlowMole,founded especially for this purpose, starts professional installationof cables and utility pipes.

1987 First with two, then with four bore rigs HDD technology is employedin the areas of Karlsruhe, Mannheim, Stuttgart, Munich andHamburg. Mostly, utility pipes for natural gas and drinking water areinstalled.

1987 First HDD applications in England

1987 Development of the first steerable German dry bore unit(Grundomole) at Tracto-Technik

1989 First bore below office tower block using HDD

1989 Development of first HDD fluid bore unit in Germany (inEttlingen/KSK and Lennestadt/GrundoJet)

1989 First HDD applications using environmental technologies in themilitary section of Frankfurt Airport (installation of extractionconduits below the runway)

1989 Simultaneous parallel pulling of several utility cables and pipes

1990 First HDD well sinking for contaminated waste sanitation inGünzburg/Bavaria

1991 Start of HDD large-scale drilling technique using Italian overheadbore rig

1991 Construction of GrundoDrill bore rigs at Tracto-Technik

1991 First HDD application in Brno (Brünn) for Eastern Europe

1991 First high-pressure injections using horizontal drilling technique(proving grounds in open pit of Goitsche near Bitterfeld)

1989–1991 Several HDD companies in Germany are established

1992 Using several HDD units simultaneously, complete local supplyunits for drinking water and natural gas are built in the newlyformed German states within a few months only.

1993 First technical meeting on steered drilling (FAGEBO)

1993 Pulling of new pipes inside old pipes using HDD while filling theannulus at the same time

1994 DCA is founded

1995 HDD installation of firmly connected grey cast iron pipes in Krefeld

Introduction 15

Figure 1.2: Substantial differences between vertical and horizontal directional drilling

1995 First application of (deep drilling) mud motors for HDD

1995 HDD sanitation of contaminated land using air suction

1996 Removal of slumps using HDD

1996 First handbook on the application of HDD is published

1998 First fully automatic prototype HDD unit tried on Söllingen airfieldnear Baden-Baden. First HDD installation of clayware pipes.

2001 Development of special HDD mud motors

2002 Installation of horizontal anchors using HDD units in Frankfurt/Main

2002 Rock drilling using hammer bore heads on GrundoPit bore rigs

2003 GW 321 as standard technical regulations for HDD installation ofgas and drinking water pipes comes into force

2004 Largest HDD unit in Europe is built in Wenden near Olpe (450-tonunit by Prime Drilling)

16 Introduction

Introduction 17

1.3 Fundamental differences between horizontal and vertical drillingtechnique

Horizontal directional drilling for trenchless installation of cables and pipes, which hasbecome quite common in the meantime, is quite often compared to the fundamentalsof vertical directional drilling as is commonly used for, or to a great extent derived from,the exploration of oil or natural gas. The latter is only true in a few cases; the numberof fundamental differences especially for small and medium-sized HDD units is ratherhigh which will be described below. Over 90 % of the HDD units constructed and inuse can be classified as small and medium-sized bore rigs (up to a max. pulling forceof 25 t) and are basically different from classical drilling technique as to their device-related construction as well as their handling (Table 1.1, Figure 1.2).

HDD mega bore rigs and vertical directional drilling units only share major technicalfeatures, i.e. vertical drill rods can also be used with HDD maxi rigs (from a pulling forceof 40 t onwards) and mega rigs; bore heads for rock drilling and flush drilling units alsohave many common features in HDD mega rig and vertical directional drilling. Asconcerns mud motors for rock drilling, special low-flow motors have in the meantimebeen developed for HDD units that show characteristic features distinguishing themfrom mud motors for oil/natural gas applications. These engineering differences haveonly just occurred during the past three years.

It is important to recognise the special and distinguishing features, which result from adrilling technology that grows more and more powerful and impart and apply themcorrectly. This correct application determines the technical superiority and marketingsuccess in the sector of new drilling technology.

Table 1.1: Fundamental differences between vertical and horizontal directional drillingtechnique

Table 1.1: Fundamental differences between vertical and horizontal directional drillingtechnique (Continuation)

18 Introduction

2 Technology of trenchless pipeline installationwith HDD

Trenchless pipeline installation using the HDD technique is a hydro-mechanical and amechanical process, it is a steerable, easy, environmentally friendly wet drillingmethod. This installation method with its near-surface, hydro-mechanical drillingfollowing road bends, too, avoids the conventional technique of pipe installation (withopen trenches, disruption of traffic). In the above system, the underground bore workson a combined principle of activity. Drilling is not primarily performed using aconventional mechanical technique but using high pressure, concentrated groundloosening water jets or bore suspension jets that penetrate from nozzles at the tip ofthe bore head and cause a hydro-mechanical penetration of unconsolidated material.For one, the loosened material is discharged with the suspension backflow along thebore rod, for the other, the unconsolidated material is partially relocated in the vicinityof the drifted bore causing a new, more compact bedding in this area by saving voidspace. At the same time, the void volume is stabilised with bore suspension that isadded to the high-pressure water jets. Mechanical detachment of consolidatedmaterial also takes place in the cross section of the bore as a secondary effect. Usingthe steerable HDD process the mechanical portion of ground detachment workincreases. When drilling in rocks using mud motors, mechanical detachment workthrough the bore head prevails – cooled and supported by bore suspension.

2.1 Methodology of drilling controlBoth vertical and lateral course control for smaller horizontal directional drilling units iseffected by the following two components:

Firstly, the bore head is equipped with a built-in transmitter creating an electro-magnetic field. This transmitter that is located directly behind the bore head in the soilcan be tracked above ground with a detection device (field intensity meter) so that theposition of the bore head can be located at all times.

Secondly, the bore head itself with its cylindrical body has an asymmetricalconstruction, a bevelled screw-down face and a lateral bevelled supporting face on thebore head. This lateral slant plane acts as a control surface in that it acts as slantsupport of the bore head by activating the passive ground thrust during steering on theopposite side of the desired direction of the curve. At any time, the position of the borehead can be retraced both from the indicator on the machine and the detection devicethat is conducted along the road directly above the bore head. In addition, anespecially flexible drill string on small horizontal directional drilling units allows aminimum curve radius of 12 m to be drilled. This wet drilling method can also handleseveral curves moving in opposite directions. Using small bore units, individual lengthsof bore sections of up to 500 m are possible with maximum depths between 8 to 12 msince detectibility of the bore head transmitters is limited to these depths. Smaller unitsare able to drill any loose sediments using equipment for unconsolidated material andany rock formations using special mud motors.

Full course control of larger horizontal directional drilling units at greater depth (usuallymore than 10 m) is for one effected through the asymmetrical, larger bore head asdescribed above, and for the other through an entirely new detection system based onelectro-magnetic precision navigation. The connecting drill rod behind the bore head

Technology of trenchless pipeline installation with HDD 19

that, in this case, must consist of anti-magnetic steel, houses sensors in a few metres’length in bar-shaped catenation, (mostly magnetometers, accelerometers and gradientsensors) continuously determining the position of the control face, the actual horizontaldrilling direction and vertical inclination. Collected data is permanently transmitted tothe control console on the bore rig via a cable running inside the bore rod (mono wire).From here, the entire bore is permanently monitored and fully controlled. When usingthis cable detection principle, aboveground detections can be dispensed with.

Since bore lengths of 2000 m and more can be realised using the larger horizontaldirectional drilling units, navigation by cable detector must function at any depth (300m and more). In any depth and distance, the steering precision of this method is always4 % relating to depth and horizontal deviation.

German horizontal directional drilling units from the 10 t-class upward are suited formost geological underground formations; using special mud motors controlled boresthrough rock are also possible.

2.2 Methodology of pipeline installationAt the start of the horizontal directional drilling (HDD) process a so-called pilot borewith the diameter of the bore head is made (Figure 2.1). This pilot bore ends at a giventarget pit. In this target pit the bore head is removed from the loaded bore rod and areamer oriented in the reverse direction is attached. This reamer is drawn back all theway through the pilot bore in reverse mode in a rotating and washover action thusupsizing the cross section of the bore (Figure 2.2). If the cross section already allowsinstallation of the desired conduit product pipe, this will be attached directly behind thereamer and drawn into the ground. An internal pipe puller connected to the reamer viaa swivel serves to pull in the pipe (Figure 2.3). The reaming diameter of the pilot boreshould be at least 30 % larger than the outer diameter of the product pipe in order tohave a sufficient amount of bentonite and drillings (swellable mixture ofbentonite/soil/clay) in the void available for an all-around an firm embedding of thepipe. For larger pipe diameters and more difficult geological underground conditions,several gradual backreaming processes are required with a spare string of bore rodsbeing attached behind the reamer during interim backreaming. It is only during the lastreaming process that the product pipe will be pulled in as well.

20 Technology of trenchless pipeline installation with HDD

Figure 2.1: Using HDD a so-called pilot bore is carried out first

Using the smaller bore units (midi rigs) product pipes with outer diameters of up to 600 mm can be installed; using the largest bore units, pipes up to a maximum of 2200 mm can be laid.

2.3 Range of horizontal drilling systemsFollowing the geological and possibly geophysical exploration and following thedefinition of the product pipe size to be installed and the desired length of the boresection, a horizontal directional drilling unit that suits the project is selected.Companies specialising in trenchless pipe installation very often have available a wholerange of different horizontal direction drilling units in widely varying performanceclasses. This allows the most suitable equipment to be selected for both constructionand installation conditions at optimal cost. Since the method of detection, as alreadyexplained, relates to the bore depth, larger bore units are equipped with an electronicnavigation system that transmits data to the control stand via cable while the smallerunits are equipped with bore head transmitters.

Horizontal directional drilling units most frequently required are in the 7 t to 20 tperformance range of thrust and pulling power as these units are very welldimensioned for the standard work of pipe installation in roads located in residentialareas and city centres. Smaller units are often used for longer house service


Figure 2.2: As a next step following the pilot bore the cross section of the borehole isupsized using a reamer

Figure 2.3: After backreaming or at the time of upsizing the cross section of the boreholethe product pipe is pulled in

connections or in very restricted environments, while the larger units are employed forinstalling pipes, in larger dimensioned under-river crossings, in environment technologyand geotechnics, in general technical construction jobs as well as for pipeline andsewer pipe installations. As a rule, the specialist company will always select theequipment best suited for the project after consulting with the customer.

2.4 Qualified realisation of trenchless pipe installation projectsAfter having specified the construction job, after an investigation into the bore pathbased on geological and possibly combining geo-radar technology and after havingselected the bore equipment, the actual construction can be carried out. In order forthe task to also comply with future requirements of the ISO 9000 quality standards, allproject planning and construction phases will be presented and subsequentlydescribed in full detail:

1. Project planning phase (obtaining existing components plan, investigating the borepath, discussing underground obstacles, determining the bore path in detail)

2. Installation product control phase

3. Machine control phase

4. Construction phase (opening of starting and target pits, bore phase, monitoring ofsafety distance, marking of bore path, welding of installation product, backreamingand pulling in phase of the installation product, closing of pits, site clean-up)

5. Follow-up phase (calibration of line, product pipe reference sample, acceptanceprotocols) and documentation. During individual project phases the following worksteps are to be considered:

2.4.1 Planning phase

• Obtaining existing components plan: obtaining any plans of third-party installationsfor the bore path requested by the customer. Comparing the customer’s projectedbore path with the underground conditions by inspecting maps providinginformation on geology, soil specification and possibly town history. Evaluatingexpert opinions on subsoil, if available. Site inspections (in some cases togetherwith the customer). Questioning of residents in respect of former buildings orunderground fills.

• Geological/geophysical inspection of bore paths (checking the customer providedexpertise on soil): Inspection and evaluation of any third-party installations.Obtaining special permits. Geological and possibly geophysical inspections into theentire width of the bore path by geological exploration of the surrounding area bythe Pürkhauer method and ram core soundings and possibly geo-radarmeasurements. Drilling conditions through the soil, possible bore obstacles (e.g.rocks, building remains, and others) as well as the actual position of third-partyinstallations by geo-radar, if applicable, are explored. By comparing third-partyinstallations with results of the geo-radar measurements and the detectedintegration points of pipes, the actual position of the pipes can be marked on theground surface.

• Discussion of underground obstacles, determination of the bore path in detail: Theresults of the geotechnical underground exploration require an in-depth discussionwith representatives of the customer. By linking the results of the exploration with


service-related parameters given by the customer and bore-related criteria of thecontractor, the bore path can be determined in detail. Based on this consultation,starting pits can be marked both on the location drawing and on the ground surface.Bore depth, crossing over and underdrilling of buried cables and pipes plus safetyclearances are entered and marked in the same way. Based on this detailedinformation the type of bore rig to be used, related boring tools and soil-specificbore suspension are determined.

2.4.2 Pipe material control phase

• Before an installation product is delivered to the jobsite certificates of quality forcable and pipe material should be to hand.

• Irrespective of the above, a visual inspection should be made after delivery; steelpipes also require a physical check. In the event of any damaged material – causedeither in production or transport - being detected, such material is either to bereturned in full or in part. Photographic documentation of the damage is advisablein any case.

• Fastest possible supply of replacement material is to be ensured.

2.4.3 Machine control phase

• Installation machines are to undergo daily checks for completeness of theirequipment and their maintenance status before starting the construction work.Compliance with the provisions for lighting and safety of the jobsite as well as formachine consumables are to be checked, too. With the help of an equipmentchecklist, any important parameters can be checked before transporting themachines to their place of operation.

• It is advisable to consider technical standards for quality tested materials andcomponents as well as for certification of the vendor at the time of manufacture ofthe boring machines.

2.4.4 Construction phase

• Opening of starting and target pits, other civil engineering: Certified contractorsshould perform third-party civil engineering work, preferably with permit. Excavationwork near buried cables and pipes, proper storage of the excavated soil, securingof excavation pits and their cleanliness require permanent monitoring.

• Boring: This service portion is in the exclusive responsibility of the horizontaldirectional drilling contractor. Before starting the bore, detection instruments are tobe calibrated and bore and mud are to be checked for optimum composition oroptimised at this time, if applicable. During the bore, results of bore path drill logdata should be observed at all times, safety distances, e.g. buried cables and pipesto be crossed, should be continuously taken into account. Unforeseen emergenciesrequiring change can only be met after having contacted the customer at least bytelephone unless possible alternatives have already been agreed upon in advance.During the bore, the course of the bore is to be marked on the road or surface andto be precisely documented in the test certificate (bore protocol). When the bore


head comes up in the target pit, high-pressure nozzles should be switched off intime.

• Welding the installation product: As a matter of principle, welding of product pipesmay only be carried out by authorised expert companies (with certificates) or byspecially trained employees. Exceptions are only possible for non-utility cables andpipes. A welding engineer or a qualified welder on site must oversee all welding.Weld parameter protocols are to be made of any welding (normally done by theprotocol plotter on the welding machine) and data to be safely stored for later use.

• Reaming and product installation phase: This part of the project, too, is thecomplete responsibility of the trenchless installation contractor. In this case, boreand mud controls are also to be performed before starting the work. The distanceof the pilot bore is to be backreamed once or several times in accordance with thedesired cross section of the pipe and the product pipe to be pulled in during the lastreaming or hole cleaning process. Before pulling in the product pipe, make sure thatthe pipe string layout is performed in such a way as not to obstruct traffic. Theactual process of pulling in the pipe is to take place avoiding friction as far aspossible; sliding rollers and cable guide pulleys must be installed without offsetbends and with minimal drag. As part of the completely installed pipe the initialpiece is to be recovered as reference sample. Drilling fluid from starting and targetpits is to be collected by specialist companies providing proof of safe disposal. Pitsthemselves should be cleaned of drilling fluid. Tools used for reaming are to bechecked for abrasion and wear. Technical maintenance and repair is required fromtime to time

• Closing of pits, cleaning of site: This task should be performed by the samecontractor who opened the pit. This is required for reasons of quality assurance andliability. When refilling the pits with excavated soil (if suitable) and classifying residueany applicable technical regulations are to be strictly complied with in order to makesure that any damage possibly occurring at a later date cannot be attributed totrenchless bore technique. Thorough cleaning of the site is to be ensured asadverse visual effects could also leave a negative impression on using thetrenchless technique.

2.4.5 Reworking phase

• Following completion of the construction work, pipes installed in the undergroundservices system or the ordnance survey system need to be updated. Together withdepth profile data the actual course of the bore, not the projected one, is to beentered in the as laid plan (using CAD if possible). Any available recorded datashould also be archived and a set of copies delivered to the customer. During finalinspection together with the customer for the purpose of preparing the bill ofquantities, the acceptance and bore protocols should be delivered, too. A referencesample of the product pipe should also be handed over to the customer.

2.5 Suitable pipe materialsUsing the mini and midi horizontal directional drilling units, nearly any pipe productsthat can withstand axial pulling and pushing forces, can be installed, for instance:

• Communication, transmitter and control cables

• Electric cables


• Polyethylene (PE) and polypropylene (PP) ductwork

• Thin-walled steel pipelines

• PE or PP water pipes

• Natural gas pipes made of PE-HD

• Flexible district heating pipes with a maximum of 220 mm OD (outer diameter)

• Drain pipes with slotted, perforated or porous surfaces up to 355 mm as well asbundled services with a maximum of six ducts with 50 mm Ø or five with 63 mm Ø

• Cast iron pipes with socket joints actuated by thrust up to 144 mm OD.

In addition to the types of pipe material mentioned above the followings types can alsobe installed using the large horizontal directional drilling units with lengths and outerdiameters of the pipes relating to the HDD unit size. For mega rigs the belowmentioned diameters do not constitute the upper limit.

• Cast iron pipes with socket joints actuated by thrust up to 842 mm OD

• Steel pipes up to 820 mm OD

• Flexible plastic pipes up to approx. 1400 mm OD

• Bundled services with an overall maximum of 1400 mm OD

• Horizontal well filter pipes

• Steel bars and ground anchors for stabilisation.

2.6 Advantages of HDD in pipeline installationThe most striking advantage is the preservation of the road or ground surface asstatic/dynamic supporting structure as there is no trench dividing the road into halvesthat react physically in different ways; on the contrary, thanks to trenchlessunderground pipe installation the strong supporting function of the road surface andsupporting layers beneath as well as undisturbed soil are preserved completely. Thepipe can be embedded firmly. It can even be embedded firmly all-around as theembedding medium usually consists of swellable clays (bentonite), the re-swellingcapacity of which in the near-pipe environment (above, on the sides, below) ensures aneven and smooth all around support. Selective loads cannot occur in the immediatevicinity of the pipe from the start, if pipes are embedded in the correct, professionalway. If handled correctly, trenchless installation of pipes offers the best possibleprerequisites for an extended pipe life.

The natural structure of the soil all around the pipe installed underground is completelypreserved. An even ground drilled in duct form based on optimum static calculationand preserved in its cohesive structure ensures even static loads above and around thepipe so that point loads are completely avoided with firm pipe embedding alreadydiscussed. The pipe is installed in a round borehole. Due to the cylindrical geometry ofthe borehole or the micro tunnel, respective tensions active in the soil will be divertedalmost ideally around the cylinder in arch form, as the untouched superstructure has avery good strong supporting effect. Solid filling of the annulus between pipe andcylindrical hollow bore ensures an even better diversion of the mechanical line oftension in the soil. Compressive strain and tensile stress are relatively balanced. If


pipes are covered in accordance with regulations, the load on the pipe is decidedlylower than with open trench constructions.

By preserving the natural structure of the soil almost no soil exchange will benecessary. Removal of excavated soil will not be required except for minimumquantities at the starting and target pits. At the same time, storage space for sand,pebble stones and crushed backfill material is saved, as the use of these naturalresources is extremely low due to the non-invasive way of construction.

As the removal of excavated spoil and the transport of the above mentioned resourcesare kept to a minimum, residents will not be annoyed as a result of high traffic andnoise and there will be no obstructions of traffic routes. A construction site that isalmost independent of weather conditions also allows high working speeds so thatonly a fraction of the time (only a quarter in some instances) will be required fortrenchless pipe installation work as compared with open trenching.

In trenchless construction, installation depths have no influence on the cost since theonly factors determining cost are boring and backreaming. The installation of pipes tobe laid at great depths can be carried out especially cost effectively using horizontaldirectional drilling.

With horizontal directional drilling using mega rigs, bores under busy traffic routes(roads, railways, waterways, runways for take-off and landing) using mega rigs do notcause any short-term traffic restrictions; with standard drilling technique there will onlybe very short-term and almost selective delays during detection of the pilot bore. Asthis is an ongoing process, traffic flows are normally restricted to a few minutes only.

In hillside locations in which any conventional open cut pipe installation requiresspecial effort and expense, horizontal drilling technique works with nearly the samebore speed as on flat terrain.

Under valuable flora and fauna, in parks, under rows of trees or habitats, horizontaldirectional drilling does not impair the natural cover in any way as roots can always becrossed underneath without any problem and without additional cost. The sameapplies to plants on riverbanks when crossing under rivers.

Since the bore head can be positioned and steered from the ground surface via amagnetic field sensor, direct steering of the bore path is possible. This allows a flexiblereaction to obstructions to be passed under or crossed over; also, buried pipes andcables (e.g. for water, gas, telephone) that might not be buried exactly in the depth andposition as indicated in the installation plans can be avoided. This requires priorlocation of the pipes and cables already installed. For power lines the bore head usedin the HDD process is equipped with a kind of warning system.

It is only after examination of all consequential costs over a longer period of time thata clear advantage can be noticed which, unfortunately, is hardly ever considered whendirectly comparing open cut trenching and no-dig Trenchless methods of pipeinstallation. Especially in case of sealed surfaces, consequential damage can beavoided that usually occurs during the second or third year following an open trenchinstallation and that presents a financial strain on the authorities responsible for roadmaintenance, i.e. local and district governments as a rule. Here, we refer to damagecaused by cracks, open cut and settling mostly appearing over the marginal areas offormerly open trenches and resulting from different physical behaviour of old, new andonce again existing surface materials. These consequential costs incurred by local,


district or federal state governments or public agencies as authorities responsible forroad maintenance can be avoided when using horizontal directional drilling.

Horizontal directional drilling with mega rigs, moreover, allows major transmissioninstallation measures in a most expedient way, but also inner-city pipe installations oflarger dimensions and higher pipe weights are possible. Pipe products made fromheavy material (ductile cast iron, steel, thick-walled PE or PP) as well as installationlengths at several meters in depth or heavy, even rocky subsoil can be mostexpediently handled by mega rigs and are much more attractive both from a technicaland economic standpoint as compared with the open trenching method. Especially forthe installation of gradient drain pipes characterised by considerable depths employingthe HDD method using mega rigs even in less densely populated areas and for newdevelopments of residential areas is attractive, since the lower degree of technical andecological complexity usually translates into lower cost.


Horizontal Drilling International SAS

Taking care of your pipeline and the

environment

Since its inception in 1984, HDI expertise in Horizontal

Directional Drilling projects has contributed to successes in

over 35 countries, with more than 1500 completed large

crossings.

HDI has the skills and equipment to perform crossings

through alluvial soils and many types of rock, for lengths up

to 2000 meters and for diameters up to 48".

Rigs of 2500 kN pulling capacity

and of 150 KNm torque

Wide range of Applications:

Water – Gas – Oil –

Optic fiber – Electricity …

Immeuble Le Guillaumet

60, avenue du Général de Gaulle

92800 Puteaux - France

Tel. +33.1.55 91 09 09 - Fax. +33.1.55 91 09 05

[email protected] - http://www.hdi.fr

Documents

HDD-Practice Handbook