ASTM F1962-22

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F1962 − 22
Standard Guide for
Use of Maxi-Horizontal Directional Drilling for Placement of
Polyethylene Pipe or Conduit Under Obstacles, Including
River Crossings
This standard is issued under the fixed designation F1962; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 This guide describes the design, selection
ization established in the Decision on Principles for the
considerations,andinstallationproceduresfortheplacementof
Development of International Standards, Guides and Recom-
polyethylene (PE) pipe or conduit below ground using maxi-
mendations issued by the World Trade Organization Technical
horizontaldirectionaldrillingequipment.Thepipesorconduits
Barriers to Trade (TBT) Committee.
may be used for various applications including
telecommunications, electric power, natural gas, petroleum,
2. Referenced Documents
water lines, sewer lines, or other fluid transport.
2.1 ASTM Standards:
1.2 Horizontal directional drilling is a form of trenchless
D420Guide for Site Characterization for Engineering De-
technology. The equipment and procedures are intended to
sign and Construction Purposes
minimize surface damage, restoration requirements, and dis-
D422Test Method for Particle-SizeAnalysis of Soils (With-
ruption of vehicular or maritime traffic with little or no
drawn 2016)
interruption of other existing lines or services. Mini-horizontal
D1586TestMethodforStandardPenetrationTest(SPT)and
directional drilling (mini-HDD) is typically used for the
Split-Barrel Sampling of Soils
relatively shorter distances and smaller diameter pipes associ-
D1587Practice for Thin-Walled Tube Sampling of Fine-
ated with local utility distribution lines. In comparison, maxi-
Grained Soils for Geotechnical Purposes
horizontaldirectionaldrilling(maxi-HDD)istypicallyusedfor
D2113Practice for Rock Core Drilling and Sampling of
longer distances and larger diameter pipes common in major
Rock for Site Exploration
river crossings. Applications that are intermediate to the
D2166Test Method for Unconfined Compressive Strength
mini-HDD or maxi-HDD categories may utilize appropriate
of Cohesive Soil
“medi”equipmentofintermediatesizeandcapabilities.Insuch
D2435Test Methods for One-Dimensional Consolidation
cases, the design guidelines and installation practices would
Properties of Soils Using Incremental Loading
follow those described for the mini- or maxi-HDD categories,
D2513Specification for Polyethylene (PE) Gas Pressure
as judged to be most suitable for each situation.
Pipe, Tubing, and Fittings
1.3 Thevaluesstatedininch-poundunitsaretoberegarded
D2850Test Method for Unconsolidated-Undrained Triaxial
as standard. The values given in parentheses are mathematical
Compression Test on Cohesive Soils
conversions to SI units that are provided for information only
D3035SpecificationforPolyethylene(PE)PlasticPipe(DR-
and are not considered standard.
PR) Based on Controlled Outside Diameter
1.4 This standard does not purport to address all of the
D4186Test Method for One-Dimensional Consolidation
safety concerns, if any, associated with its use. It is the Properties of Saturated Cohesive Soils Using Controlled-
responsibility of the user of this standard to establish appro-
Strain Loading
priate safety, health, and environmental practices and deter- D4220 Practices for Preserving and Transporting Soil
mine the applicability of regulatory limitations prior to use.
Samples
Section6containsgeneralsafetyinformationrelatedtotheuse
of maxi-horizontal directional drilling equipment.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This guide is under the jurisdiction ofASTM Committee F17 on Plastic Piping contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Systems and is the direct responsibility of Subcommittee F17.67 on Trenchless Standards volume information, refer to the standard’s Document Summary page on
Plastic Pipeline Technology. the ASTM website.
Current edition approved Nov. 15, 2022. Published December 2022. Last The last approved version of this historical standard is referenced on
previous edition approved in 2020 as F1962–20. DOI: 10.1520/F1962-22. www.astm.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1962 − 22
D4318Test Methods for Liquid Limit, Plastic Limit, and 3.1.1 horizontal directional drilling, HDD, n—a technique
Plasticity Index of Soils for installing pipes or utility lines below ground using a
D4767Test Method for Consolidated Undrained Triaxial surface-mounted drill rig that launches and places a drill string
Compression Test for Cohesive Soils at a shallow angle to the surface and has tracking and steering
D5084Test Methods for Measurement of Hydraulic Con- capabilities.
ductivity of Saturated Porous Materials Using a Flexible 3.1.1.1 Discussion—Thedrillstringcreatesapilotborehole
Wall Permeameter in an essentially horizontal path or shallow arc which may
F714Specification for Polyethylene (PE) Plastic Pipe (DR- subsequently be enlarged to a larger diameter during a second-
PR) Based on Outside Diameter ary operation which typically includes reaming and then
F1804Practice for DeterminingAllowable Tensile Load for pullback of the pipe or utility line. Tracking of the initial bore
Polyethylene (PE) Gas Pipe During Pull-In Installation pathisaccomplishedbyamanuallyoperatedoverheadreceiver
F2160Specification for Solid Wall High Density Polyethyl- or a remote tracking system. Steering is achieved by control-
ene (HDPE) Conduit Based on Controlled Outside Diam- ling the orientation of the drill head which has a directional
eter (OD) bias and pushing the drill string forward with the drill head
F2620PracticeforHeatFusionJoiningofPolyethylenePipe oriented in the direction desired. Continuous rotation of the
and Fittings drill string allows the drill head to bore a straight path. The
procedure uses fluid jet or mechanical cutting, or both, with a
2.2 Other Standards:
low, controlled volume of drilling fluid flow to minimize the
ANSIPreferred Number Series 10
creation of voids during the initial boring or backreaming
ANSI/EIA/TIA-590StandardforPhysicalLocationandPro-
operations. The drilling fluid helps stabilize the bore hole,
tection of Below-Ground Fiber Optic Cable Plant
remove cuttings, provide lubricant for the drill string and
AWWA C901Polyethylene (PE) Pressure Pipe and Tubing,
plastic pipe, and cool the drill head. The resultant slurry
3/4in.(19mm)through3in.(76mm),forWaterService
surrounds the pipe, typically filling the annulus between the
AWWAC906Polyethylene (PE) Pressure Pipe and Fittings,
pipe and the bored cavity.
4 in. thru 65 in. (100 mm through 1650 mm), for
Waterworks
3.1.2 maxi-horizontal directional drilling, maxi-HDD, n—a
OSHA-3075Controlling Electrical Hazards
classofHDD,sometimesreferredtoasdirectionaldrilling,for
GR356 Generic Requirements for Optical Cable Innerduct
boring holes of up to several thousand feet in length and
placing pipes of up to 48 in. (1 ⁄4 m) diameter or greater at
3. Terminology
depths up to 200 ft (60 m).
3.1.2.1 Discussion—Maxi-HDD is appropriate for placing
3.1 Definitions:
pipes under large rivers or other large obstacles (Fig. 1).
Tracking information is provided remotely to the operator of
the drill rig by sensors located towards the leading end of the
AvailablefromtheElectronicsIndustriesAssociation,2001PennsylvaniaAve.,
drill string. Cutting of the pilot hole and expansion of the hole
N.W., Washington, DC, 20006.
is typically accomplished with a bit or reamer attached to the
Available fromAmericanWaterWorksAssociation (AWWA), 6666W. Quincy
Ave., Denver, CO 80235, http://www.awwa.org.
drill pipe, which is rotated and pulled by the drilling rig.
Available from the Occupational Health and Safety Administration, 200
3.1.3 mini-horizontal directional drilling, mini-HDD, n—a
Constitution Ave. N.W. Washington, DC 20210.
Available from Ericsson, Ericsson Information Superstore, https:// class of HDD, sometimes referred to as guided boring, for
telecominfo.njdepot.ericsson.net.
FIG. 1 Maxi-HDD for Obstacle (for example, River) Crossing
F1962 − 22
boringholesofuptoseveralhundredfeetinlengthandplacing proposedcrossingsite.Horizontalandverticalreferencesmust
pipes of typically 12 in. (300 mm) or less nominal diameter at be established for referencing hydrographic and geotechnical
depths typically less than 25 ft (7 m).
data. The survey should typically include overbank profiles on
3.1.3.1 Discussion—Polyethylene pipe selection and usage
the anticipated path center-line, extending about 150 ft (75 m)
for mini-HDD is discussed extensively MAB-7 2020, “Guide-
landward of the bore entry point to the length of the (pre-
lines for Use of Mini-Horizontal Directional Drilling for
fabricated) pull section landward of the bore exit point. The
Placement of HDPE (PE4710) for Municipal Applications”,
survey information should be related to topographical features
publishedbytheMunicipalAdvisoryBoardofthePlasticsPipe
inthevicinityoftheproposedcrossing.Existingtopographical
Institute (PPI) (1)
informationmaybeavailablefromtheU.S.GeologicalSurvey,
3.1.3.2 Discussion—Mini-HDD is appropriate for placing
or Federal, state, or county publications.Aerial photographs or
local distribution lines (including service lines or laterals)
ordnance surveys may be useful, especially for crossing
beneathlocalstreets,privateproperty,andalongright-of-ways.
land-based obstacles in urban areas, since these may indicate
The creation of the pilot bore hole and the reaming operations
the presence of demolished buildings and the possibility of old
are typically accomplished by fluid jet cutting or the cutting
foundations, as well any filled areas (4). It is also necessary to
torque provided by rotating the drill string, although mud
check available utility records to help identify the precise
motors powered by the drilling fluid are sometimes used for
location of existing below-ground facilities in the vicinity,
hard or rocky soil conditions. The use of such mud motors
including electric power, natural gas, petroleum, water, sewer,
would only be applicable for the larger mini-HDD machines.
or telecommunications lines. The presence of existing
Thelocatingandtrackingsystemstypicallyrequireamanually
pipelines, support pilings, etc., containing significant steel
operated overhead receiver to follow the progress of the initial
mass should be noted since this may cause interference with
pilot bore. The receiver is placed above the general vicinity of
magnetically sensitive equipment guidance or location instru-
the drill head to allow a determination of its precise location
mentation.
and depth, indicate drill head orientation for determining
4.2.1.1 Drill Rig (Bore Entry) Side—The available area
steering information to be implemented from the drill rig.
requiredonthesideofthedrillrigmustbesufficientfortherig
3.1.4 pipe dimension ratio, DR, n—the average specified
itself and its ancillary equipment. In general, the size of the
diameter of a pipe divided by the minimum specified wall
requiredareaontherigsidewilldependuponthemagnitudeof
thickness.
the operation, including length of bore and diameter of pipe to
3.1.4.1 Discussion—For pipes manufactured to a controlled
be placed. Typically, a temporary workspace of approximately
outside diameter (OD), the DR is the ratio of pipe outer
150 ft (45 m) width by 250 ft (75 m) length will be sufficient.
diameter to minimum wall thickness. The standard dimension
These dimensions may vary from 100 by 150 ft (30 by 45 m)
ratio (SDR) is a specific ratio of the outside diameter to the
for shorter crossings of 1000 ft (300 m) or less, to 200 by 300
minimum wall thickness as specified by ANSI Preferred
ft (60 by 90 m) for medium or long crossings.
Number Series 10.
4.2.1.2 Water Supply—Water storage and facilities for
NOTE1—LowerDRvaluescorrespondtothickerpipewallsforagiven
mixing, storing, and pumping drilling fluid will require signifi-
diameter.
cantspace.Althoughitisstandardpracticetodrawfreshwater
4. Preliminary Site Investigation
found at the location for mixing the drilling fluid, alternate
water supplies may be required to obtain proper drilling fluid
4.1 General Considerations—Amaxi-HDD project, such as
characteristics. Hard or salty water is undesirable, although
that associated with a river crossing, is a major event that will
additives may be used to create the proper pH value. It may be
require extensive and thorough surface and subsurface inves-
necessary to provide access for trucks to transport water or to
tigations. Qualified geotechnical engineers should perform the
provide for the installation of a relatively long surface pipe or
work for the owner in preparation for planning and designing
of the bore route. The information should also be provided to hose connecting a remote hydrant.
the potential contractors to provide guidance for the bidding
4.2.1.3 Pipe (Bore Exit) Side—Assuming the pipe to be
stage and subsequent installation. The contractor may perform
placed is too large a diameter to be supplied on a reel (for
additional investigations, as desired. Since typical maxi-HDD
example, larger than 6 in. (150 mm)), sufficient space is
projectsrepresentrivercrossings,thefollowingproceduresare
requiredatthesideoppositethatofthedrillrig,wherethebore
described in terms of the specific investigations and issues
willexitandthepipebeinserted,toaccommodateacontinuous
arisinginsuchcases.Thegeneralprocedures,however,maybe
straightlengthofpre-fabricatedpipe.Thespaceforthestraight
appropriately interpreted to also apply to non-river crossings,
lengthwillbeginapproximately50to100ft(15to30m)from
such as under land-based obstacles including highways,
the anticipated bore exit and extend straight landward at a
railways, etc.
width of 35 to 50 ft (10 to 15 m), depending upon the pipe
4.2 Surface Investigation (2, 3) diameter. In the immediate vicinity of the bore exit (pipe
entry), an area of typically 50 ft (15 m) width by 100 ft (30 m)
4.2.1 Topographic Survey—A survey should be conducted
to accurately define the working areas described in 4.1 for the length is required; for relatively large diameter pipes (larger
than24in.(600mm),orincasesofdifficultsoilconditions,an
8 area of 100 ft (30 m) width by 150 ft (45 m) length should be
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
this standard. provided.
F1962 − 22
4.2.2 Hydrographic/Potamological Survey—For crossing beexamined.Theresultsofthisstudywillbeusedtodefinethe
significant waterways, a survey should be conducted to accu- initially recommended bore penetration profile path.
4.3.2 Test Borings (2, 3, 5)—Site-specific data must be
rately describe the bottom contours and river stability to
establish suitability for the design life of the pipeline. obtainedtofullycharacterizeandverifytheconditionsthrough
which the proposed bore path will be created. Refer to Guide
Typically, depths should be established along the anticipated
D420, Test Method D1586, Test Method D1587, Test Method
center-line, and approximately 200 ft (60 m) upstream and
D2113andPracticeD4220.Datacollectionshouldbeaimedat
downstream; closer readings may be required if it is necessary
identifying earth materials at the site and at exploring subsur-
to monitor future river activity. Consideration should be given
face stratification (including identification of the boundary
to future changes in river bank terrain. Washouts, bank
between rock and other strata, presence of cobbles or boulders
migrations, or scour can expose pipe.
and other anomalies such as old tree stumps and fill debris).
4.2.3 Drilling Fluid Disposal—The means for disposal of
The location, depth, and number of borings should be deter-
the drilling fluid wastes must be considered. The volume of
mined by the engineer based on the preliminary study, antici-
drilling fluid used will depend upon the soil characteristics but
patedfuturechangesinsiteconditions(rivermeanders,scours,
istypicallyontheorderof1to3timesthevolumeofremoved
etc.), and modifications of soil conditions during construction.
soil. Most drilling fluids use bentonite or polymer additives
These borings should be located at a sufficient lateral distance
which are not generally considered to be hazardous. However,
(to either side) from the proposed bore path to avoid boring
local regulations should be followed regarding disposal.
into the test hole, and the holes should be sealed with grouting
4.2.3.1 Drilling Fluid Recirculation —Occasionally,drilling
to avoid potential leakage paths for drilling fluid during the
fluid recirculation is used to reduce overall material and
actual installation. Following completion of the detailed route
disposal costs. If drilling fluid recirculation is contemplated, a
design (Section 7), additional test borings may be desirable at
means must be considered for transporting any fluid exhausted
critical points such as bends.
from the opposite (bore exit) side, during the pullback
NOTE 2—In environmentally and other sensitive areas, possible restric-
operation, to the rig side. This may be accomplished by truck,
tions may exist on the location or number of test borings.
barge, or a temporary recirculation pipe line on the bottom of
4.3.3 In addition to test borings, dynamic cone testing or
the waterway (for river-crossings). The recirculation line must
developing non-intrusive techniques such as ground penetrat-
be adequate to prevent accidental discharge into the waterway.
ing radar or sonar may be used to identify stratification and
4.3 Subsurface Investigation—The overall technical and
areaswithanomalies.Suchprobingtechniquesmaybeapplied
economic feasibility of the maxi-HDD process is highly
in the proximity of known conditions determined by a boring
dependent upon the properties of the soil formation through
to obtain proper calibration, and then extended towards un-
which the penetration will be accomplished. Thus, an accurate
testedareasatrelativelycloseintervalstoidentifyirregularities
and thorough geotechnical investigation must be performed by
between borings. If needed, additional borings may then be
a qualified engineer, including review of existing information
made at intermediate points of interest (4, 5).
and site specific studies for the proposed location. This
4.3.4 Soil Analysis (3, 6, 7)—The geotechnical study should
informationwillbeusedtoproducedesigndrawings(including
evaluate several parameters, including soil classifications,
final bore route, pipe design, and bore design), construction
(Refer to Test Methods D4318 and D422.) strength and
specifications, and permit applications as well as to provide
deformationproperties,(RefertoTestMethodsD1586,D2166,
information for the contractors upon which to select appropri-
D2435, D2850, D4186, and D4767.) and groundwater table
ate tools and methods for the actual construction. While the
behavior. (Refer to Test Method D5084.)Although some field
guidelines given in the following sections point out general
evaluation and in-situ testing should be included, the geotech-
procedures or types of information, or both, which could be
nicalinvestigationshouldemphasizelaboratorytestinginorder
developed, unforeseeable site-specific variables make the thor-
to obtain more accurate and meaningful quantitative results. If
oughness and accuracy of any site characterization study
rockisencountered,theboringsshouldpenetratesufficientlyto
directly dependent on the skill, experience, and inquisitiveness
verify whether or not it is bedrock. The relevant soil testing
oftheinvestigatingengineer.Therefore,theinvestigatorshould methods listed in Section 2 should be followed. In general, the
define the configuration, extent, and constituency of the inves- following specific data should be obtained from the borings:
tigation. Site characterization information must go beyond just 4.3.4.1 Standard classification of soils, (Refer to Test
defining soil conditions along the bore path to include a
Method D4318),
forecast of future conditions (that is, river meanders and
4.3.4.2 Gradation curves for granular soils, as described in
scours)andtoanticipatetheeffectofthemaxi-HDDprocesson Test Method D422,
site conditions.
4.3.4.3 Standardpenetrationtestvalues,asdescribedinTest
Method D1586,
4.3.1 Preliminary Study—The subsurface investigation
4.3.4.4 Coredsamplesofrockwithrockqualitydesignation
should begin with a review of existing data such as may be
(RQD) and percent recovery,
obtained from published soil reports (for example, Soil Con-
servation Service Report, U.S. Geological Survey, U.S. Army 4.3.4.5 Unconfined compressive strength, as described in
Test Method D2166,
Corps of Engineers reports, etc.) or records from previous
4.3.4.6 Moh’s hardness for rock samples,
construction projects. In particular, data from nearby pipe or
cable river-crossings, or bridge foundation construction should 4.3.4.7 Possible contamination (hazardous waste),
F1962 − 22
4.3.4.8 Groundwater location, type, and behavior, and conditions. The conditions under which “difficulties may
4.3.4.9 Electrical resistivity or mineralogical constituents. occur” may require modifications of routine procedures or
4.3.5 For river crossings, the results from the preliminary equipment, such as the use of special purpose drill heads or
study and site specific tests should be combined in a compre- optimized drilling fluids. Some cases will entail “substantial
hensive report describing the geotechnical subsurface condi- problems” and may not be economically feasible for direc-
tions beneath the river bottom plus the stream’s potential for tional drilling using present technology. The potential for
meandering and scouring. The results must then be considered problems to occur increases with the presence of gravels,
by the owner, the engineer, and potential contractors, with boulders, or cobbles or with transitions from non-lithified
regard to compatibility with the state-of-the-art of directional material into solid rock. In such cases, other drilling locations
drilling technology for cost-effectively completing the task. If orconstructionalternativesshouldbeconsideredunlessspecial
necessary, the crossing location may be altered to a more circumstances dictate the need for directional drilling at the
favorable crossing site. In this case, many of the surface and presentlocation,evenathighcostsassociatedwithspecialrock
subsurface investigations may have to be repeated for the new drilling techniques, etc.
proposed crossing location and bore path.
5. Safety and Environmental Considerations
4.3.6 Feasibility—Soil conditions are a major factor affect-
ing the feasibility and cost of using maxi-HDD in a given
5.1 General Considerations—Injurytopersonnelmayresult
geographic area. Table 1 indicates the suitability of horizontal
fromthemechanicalandhydraulicmachineoperationsdirectly
directional drilling as a function of the general characteristics
related to the drilling operation or from striking of electric
of the soil conditions in the area and depths of interest (4, 6).
power lines or buried pipelines. In addition, the scale of
The “generally suitable” category presumes knowledgeable,
maxi-HDD operations may involve additional equipment and
experienced contractors or personnel using appropriate equip-
accessories required for the lifting and handling of heavy drill
ment.Suchcontractorsareassumedtohaveaminimumofone
rods, drill heads, reamers, etc., as well as the product pipe or
year field experience and completed approximately 30 000 ft
conduit. Additional precautions relating to specific auxiliary
(10 km) of construction in related projects. The size and type
equipment must be followed, but is beyond the scope of this
machinesconsideredappropriateforparticularinstallationsare
standard.Non-essentialpersonnelandbystandersshouldnotbe
a function of bore length, final hole diameter, and soil
allowed in the immediate vicinity of the maxi-HDD equip-
conditions.Various type drill heads, mud motors, reamers, and
ment.Barriersandwarningsshouldbeplacedaminimumof30
drilling fluid capabilities are available for various ground
ft (10 m) from the edge of the equipment or associated
hardware. Safety precautions are to be followed by all person-
nel and at both ends of the bore path. Inadvertent contact with
TABLE 1 Soil Conditions and Suitability of Horizontal Directional
A
electric power, natural gas, or petroleum lines may result in
Drilling
Soil Conditions Generally Difficulties Substantial hazards to personnel or contamination. If possible, any in-
Suitable May Occur Problems
service pipeline in the proximity of the bore should be
Soft to very soft clays, silts, and X
de-activated during the construction. In general, the possibility
organic deposits
of injury or environmental impact caused by damage to
Medium to very stiff clays and silts X working or powered subsurface facilities or pipelines during
the initial boring or backreaming operations is reduced by
Hard clays and highly weathered X
appropriate adherence to regulations and damage prevention
shales
procedures, as outlined in Section 6.
Very loose to loose sands above and X
5.2 Work Clothing—Warning—Loose clothing or jewelry
below the water table (not more than
30 % gravel by weight)
shouldnotbewornsincetheymaysnagonmovingmechanical
parts. Safety glasses or OSHAapproved goggles, or both, and
Medium to dense sands above or X
OSHA approved head gear should be worn at all times.
below the water table (not more than
30 % gravel by weight)
Protective work shoes and gloves must be worn by all
personnel.
Very loose to dense gravelly sand, X
(30 % to 50 % gravel by weight)
5.3 Machine Safety Practices—Contractors must comply
with all applicable OSHA, state, and local regulations, and
Very loose to dense gravelly sand X
(50 % to 85 % gravel by weight) accepted industry practices.All personnel in the vicinity of the
drill rig or at the opposite end of the bore must be properly
Very loose to very dense gravel X
trainedandeducatedregardingthepotentialhazardsassociated
Soils with significant cobbles, X
with the maxi-HDD equipment. For electrical hazards, see
boulders, and obstructions
OSHA 3075. Personnel must be knowledgeable of safe oper-
ating procedures, safety equipment, and proper precautions.
Weathered rocks, marls, chalks, and X
firmly cemented soils
Courses and seminars are available in the industry, including
training provided by the equipment suppliers.
Slightly weathered to unweathered X
5.3.1 The operation of the drill rig requires rotation and
rocks
A advancement or retraction of the drill rods. Drill rig operation
For additional information, see Ref. (6).
istypicallyaccomplishedusingchaindrives,gearsystems,and
F1962 − 22
vises which may potentially lead to personal injury due to the unless it becomes mixed with toxic pollutants. The waste
moving mechanical components. All safety shields or guards material is usually considered as typical excavation spoils and
must be properly mounted. The equipment must be checked at can be disposed or by means similar to other spoils. If other
the beginning of each work day to verify proper operation. additives are of concern or hazardous material disposal is
required, it may be necessary to de-water the spoils, transport
5.3.2 HydraulicFluid—Thehydraulicoillinespoweringthe
drill rig operate under pressures of several thousand psi the solids to an appropriate disposal site, and treat the water to
meet disposal requirements.
(hundredsofbars).Thehosesandconnectorsmustbeproperly
maintained to avoid leaks. 5.4.2 The utility access pits which may be present at both
ends of the bore are convenient receptacles for collecting used
5.3.2.1 Warning—If a leak is suspected, it should be
drilling fluid. If not present for utility access, small pits should
checked by using a piece of cardboard or other object, but not
be provided at both ends to serve as such receptacles. Depend-
hands or any other part of the body. The high pressure
ing upon soil permeability, the pits may be lined with an
hydraulic fluid can penetrate the skin, burn, or cause blood
appropriate material or membrane. The pits should be emptied
poisoning. Before disconnecting any hydraulic lines, the sys-
as necessary. Some maxi-HDD systems use drilling fluid
tem pressure should be relieved.
recirculating systems to reduce the volume of spoils. If the
5.3.3 Drilling Fluid—Drilling fluid pressures will vary de-
geotechnical investigation revealed the existence of soil con-
pending upon the equipment design and operator preference;
ditions conductive to fluid migration, such as through pre-
pressures of several thousand psi (hundreds of bars) are
fractures in surrounding clay or soil mass permeability, this
possible. The hoses and connections must be properly main-
condition must be anticipated and accounted for in the drilling
tained to avoid leaks.
operation.
5.3.3.1 Warning—Suspected leaks should be checked by
using a piece of cardboard or other object. Avoid the use of
6. Regulations and Damage Prevention
hands or any other part of the body to check for a leak. Before
6.1 General Considerations—The owner of the proposed
individual drill rods are inserted or removed from the drill
pipeline should obtain any required drilling permits and is
string, it must be verified that the drilling fluid pressure has
responsible for obtaining approvals from the Federal, state, or
beenshutoffandallowedtodecrease;otherwise,highpressure
localjurisdictionsorotheragenciesthatmaybeaffectedbythe
fluid will squirt from the joint and possibly cause injury to
work. The preliminary investigations (Section 4) should iden-
personnel. The drilling fluid pressure gage must be checked to
tify appropriate site locations and paths, including safe sepa-
verify the pressure has been relieved before disconnecting any
rations from other facilities such as electric power, natural gas,
rods.
orpetroleumlines.Iftheconstraintsforaparticularmaxi-HDD
NOTE 3—If the pressure does not decrease in a short interval following
bore are such as to be in the vicinity of known facilities, the
pressure shut off, the fluid jet openings at the drill head may be clogged.
affected owners must be contacted and strict procedures for
Special care must then be made when disconnecting the rod. It may be
location and marking followed. If a maxi-HDD bore intercon-
necessarytoretractthedrillstringorexposethedrillheadtoclearthejets
nects points under the jurisdiction of several states or govern-
before continuing the operation. To avoid injury from the drill head and
drilling fluid, all personnel should maintain a safe distance from the exit
ing bodies, then the regulations of all parties must be
pointoftheboreasthedrillheadsurfaces.Thepressureshouldbeshutoff
considered, including relevant permits. Special restrictions
as soon as the drill head exits.
may exist, including restoration regulations, in environmen-
5.4 Construction Effects on Site—It is assumed that the
tally sensitive habitat areas.
preliminary site investigations included analyses to verify the
6.2 Environmental, Health, and Safety Plan—When
stability of embankments, roads, or other major features to be
required, each contractor that will work on the project must
traversed. It is necessary to ensure that the maxi-HDD opera-
submit an environmental, health, and safety plan. Items to
tion will not negatively impact the site upon completion. In
consider are the responsibilities of the plan, reporting, em-
many cases, it will be appropriate to use grouting to seal the
ployee training, MSDS sheets for materials being used, emer-
final bore path hole or the end portions of the hole following
gency telephone numbers for police, fire department, and
the installation of the pipe to prevent future flow or environ-
medical assistance, fire prevention, sanitation, and industrial
mental contamination. Particularly sensitive areas include
hygiene.
statutorily designated areas, such as wetlands, natural and
6.3 Environmental and Archaeological Impact Study—Most
scenic waterways, or contaminated or waste disposal sites. If
projects using maxi-HDD will require procurement of various
the bore will pass through, or in close proximity to, a
environmental permits. When an environmental permitting
contaminated area, special spoils monitoring and disposal
plan must be prepared, it should include a list of required
procedures must be followed, consistent with applicable
permits (for example, USAE, USEPA), the time needed to
Federal, state, or local regulations.
prepare permits, and an estimated date of issuance. Items to
5.4.1 Drilling Fluid—The most common drilling fluid addi-
consider are solid and hazardous materials and waste
tive is bentonite, a naturally occurring clay. When added to
management, wetlands, burial grounds, land use, air pollution,
water, the resulting fluid provides desired properties including
noise, water supply and discharge, traffic control and river and
viscosity, low density, and lubricity. The bentonite material
railroad transportation.
usedshouldbeNationalSanitationFoundation(NSF)certified.
Disposal should be in accordance with local laws and regula- 6.4 Waterways (see ANSI/EIA/TIA-590)—The U.S. Army
tions. The bentonite-water slurry is not a hazardous material Corps of Engineers (USAE) regulates activities involving
F1962 − 22
interstatebodiesofwater,includingmarshesandtributaries,as Thisappliestobendsinhorizontal(plan)orvertical(profile)
wellasintrastatewaterswhichcouldaffectinterstateorforeign planes.
commerce. The organization is responsible for work affecting
7.3 The proposed path should avoid unnecessary bends.
such waterways, including to the headwaters of freshwater
Such trajectories may be difficult to follow and may lead to
streams, wetlands, swamps and lakes. The Regional District
oversteering and excessive bends, resulting in increased
Engineer of the USAE will advise applicants of the types of
stresses in the drill rods and greater required pulling forces
permitsrequiredforsuchproposedprojects.Inaddition,astate
duringtheinstallationofthepipe.Thelocalradiusofcurvature
orlocal,orboth,agencyenvironmentalreviewandpermitmay
of the path at any point may be estimated by:
be required.
∆S
R 5 (2)
6.5 Railroad Crossings (see ANSI/EIA/TIA-590)—The
∆φ
chief engineer of the railroad should be consulted for the
where:
approvedmethodsof crossing the railroad line. For spurtracks
R = local radius of curvature along path segment, ft (m),
or sidings, the tract owner should be consulted. Railroads
∆S = distance along path, ft (m), and
normally require cased pipes at crossings to prevent track
∆φ = angular change in direction, rad.
washouts or damage in the event of pipeline rupture. (At the
NOTE4—Theangleinradiansisequaltotheangleindegrees×0.0175.
time of writing of this standard, an American Railway Engi-
(One radian equals 57.3°.)
neeringAssociation (AREA) committee is studying the use of
Thus, if ∆S is selected to be equal to 30 ft (10 m) (for
HDD for uncased and cased crossing of railroads for both
example, one rod length for some maxi-HDD machines) a
plastic and steel gas pipelines.)
change of 0.1 rad (6°) corresponds to a radius of curvature of
300 ft (100 m).
7. Bore Path Layout and Design
7.4 BorePathsProfile(VerticalPlane)Trajectory (2, 3)—A
7.1 General Considerations—For maxi-HDD projects, such
typical obstacle crossing, such as that represented by a river is
as river crossings, the bore path should be designed and
illustrated in Fig. 1.
specified by the engineer representing the owner prior to the
7.4.1 The following parameters must be specified in defin-
contractorbiddingprocess.Baseduponthepreliminarysurface
ing the bore path:
andsubsurfaceinvestigations,thepathwillbeselectedtoplace
7.4.1.1 Bore entry (pipe exit) point,
the pipe within stable ground and isolated from river activities
7.4.1.2 Bore exit (pipe entry) point,
forthedesignlifeoftheutilityline.Thegroundthroughwhich
7.4.1.3 Bore entry (pipe exit) angle,
the path will traverse must be compatible with maxi-HDD
7.4.1.4 Bore exit (pipe entry) angle,
technology.Ingeneral,formaxi-HDDprojects,thedesignpath
7.4.1.5 Depth of path, (for example, depth of cover of pipe
willliewithinaverticalplane.Ifnecessary,lateralcurvatureis
beneath river bottom), and
possible, consistent with the capabilities of the equipment and
7.4.1.6 Path curvatures.
the product pipe. The path should be clearly designated in an
7.4.2 Bore Entry (Pipe Exit)—The bore entry point must be
integrated report summarizing the results of the surface and
accurately specified consistent with the pipe route, equipment
subsurface investigations, and should be used for pricing,
requirements, and preliminary topographical investigations.
planning, and executing the operation.
Bore entry angles should be in the range of 8 to 20° (0.15 to
7.2 Steering and Drill Rod Constraints—The planned path
0.35rad)fromthegroundsurface,preferably12to15°(0.20to
mustbeconsistentwiththesteeringcapabilityofthedrillstring
0.25rad)fromthegroundsurface.Theseanglesarecompatible
and the allowable radius of curvature of the steel drill rods
with typical equipment capabilities.
baseduponthecorrespondingbendingstressesinthesteelrods
7.4.3 Bore Exit (Pipe Entry)—The bore exit point must also
and joints. Although some soil conditions will inhibit sharp
be accurately specified consistent with the pipe length and
steering maneuvers, path limitations will often be based upon
topographical investigations. Bore exit angles should be rela-
fatiguestrengthconsiderationsoftherods.Agivenrodmaybe
tively shallow, preferably less than 10° (0.15 rad). A shallow
able to withstand a single bend cycle corresponding to a
angle will facilitate the insertion of the pipe into the bore hole
relatively sharp radius of curvature, but the rotation of the rod
while maintaining the minimum radius of curvature require-
during the boring operation results in flexural cycles which
ments. Relatively steep angles will require greater elevation of
may eventually cause cumulative fatigue failure. The diameter
the pipe to maintain the required bend radii.
of the drill rod is an important parameter affecting its stiffness,
7.4.4 Path Profile—The proposed path should optimally lay
steering capability, and the allowable bend radii. A conserva-
withinaverticalplaneincludingtheboreentryandexitpoints.
tive industry guideline indicates the minimum bend radius
The arcs of the bore path and straight sections (that is, after
should be approximately:
achievingdesireddepth)mustbedefined,includingtheradiiof
R 51200 D (1)
~ ! curvature and approximate points of tangency of curved and
rod min rod
straight segments. The curvatures must be compatible with
where:
both the steel drill rods (Eq 1) and the PE pipe or conduit
(R ) = medium recommended bend radius of drill rod,
rod min
(Section 8). It should be noted that even larger bend radii
in. (mm), and
(lower curvatures) will further reduce lateral flexural bending
D = nominal diameter of drill rod, in. (mm).
rod
loads on the pipe and drill rods as they traverse the route,
F1962 − 22
thereby helping avoid additional increases in tensile loads diameter pipe of continuous length may be provided on reels.
associatedwiththeirstiffnesseffects.Typically,thepathshould Table X1.1 gives modulus and strength values for typical
ensure a minimum depth of cover of 15 ft (5 m) beneath the pressure-rated HDPE and MDPE resins.
river bottom as projected over the design life of the pipe line,
8.1.3 Cable Conduit Applications —For cable conduit
including allowance for scouring (3, 5). This will overcome
applications,includingelectricpowerandtelecommunications,
buoyancy effects and help overcome the tendency for the drill
small diameter pipe may be supplied on a continuous reel
head to rise towards the free surface, thereby complicating the
including internal pull line or the cable itself, as pre-installed
steering operation.
by the manufacturer. In addition, the pipe may be provided
withtheinteriorsurfacepre-lubricated.Suchfeatureswillbein
NOTE 5—The Directional Crossing Contractors Associations (DCCA)
accordance with that specified by the owner or engineer.
(8) recommends a minimum depth of 20 ft beneath the river bottom.
Requirements for telecommunications applications, including
7.4.4.1 Average Radius of Curvature —The average radius
HDPE pipe with various internal surface profiles, including
of curvature for a path segment (that is,A-B or C-D in Fig. 1)
smoothwall or ribbed are specified in GR356.
reaching to or from a depth required to pass beneath an
obstacle, may be estimated from the bore exit or entry angle,
8.2 Pipe Loading:
respectively, and the depth of the bore:
8.2.1 Operational and Installation Loads—The pipe will be
subject to loads during its long-term operation and during the
2H
R 5 (3)
avg 2 installation process. It is the responsibility of the owner (or the
θ
owner’s contractor or engineer) to determine the design and
where:
selection of the pipe to serve the function intended and
R = average radius of curvature along path segment, ft
avg withstand the operational stresses at the directionally drilled
(m),
section as well as at other sections along the pipe line. This
θ = bore exit or entry angle to surface, rad, and
practice deals primarily with the loads imposed during the
H = depth of bore beneath surface, ft (m).
directional drilling process and earth and groundwater loads
The corresponding horizontal distance required to achieve during operation (post-installation).
the depth or rise to the surface may be estimated by:
8.2.2 Internal (Operational) Pressure Loads—It is the re-
sponsibilityoftheowner(orowner’scontractororengineer)to
2H
L 5 (4)
determinethenominaldiameterandwallthicknessappropriate
θ
for the intended application. For example, if the pipe will be
where:
usedforthepressurizedflowofliquidsorgases,itisnecessary
L = horizontal transition distance, ft (m).
to determine the nominal diameter based on flow capacity
requirements and the minimum wall thickness (or DR) to
It must be noted that departures from a uniform radius will
withstand the corresponding circumferential stresses on a long
result in locally smaller radii.
termbasis.SpecificationD2513,D3035,F714,F2160,AWWA
7.4.4.2 The resultant path will determine the stresses to be
C901, and AWWA C906 may be used to determine an initial
exerted upon the pipe during the installation and service life.
estimate of the corresponding maximum dimension ratio (DR)
The product pipe design must therefore be analyzed based
for PE pipe.
upon the final selected path, following the pipe design and
8.2.3 External (Operational) Hydraulic and Earth Loads—
selection procedures given in Section 8.
The pipe will be subjected to hydrostatic external pressure due
8. Pipe Design and Selection Considerations
to the height of water or drilling fluid (or slurry) above the
maximumdepthofplacementrelativetotheentryorexitpoint,
8.1 General Guidelines:
8.1.1 Maxi-HDD applications typically require detailed and earth loads and live loads due to load transfer through the
deformation of the soil around the borehole (9). If borehole
analysis of the pipe or conduit in relation to its intended
application. Due to the large, anticipated pulling loads and deformation is minimal (such as in rock) or does not deform
the pipe, the only loading applied to the pipe is the hydrostatic
potentially high external pressure, a careful analysis of the PE
pipe must be performed, subject to the route geometry, to external pressure. When earth load does reach the pipe, load
verifyordetermineanappropriateDR(orpipewallthickness). reductions from the geostatic stress (arching) may be antici-
The analysis should consider both the installation forces pated. The reductions may be s
...