Line 21 Segment Replacement

HDD FEASIBILITY REPORT I

Revision History:

STATUS DATE

(MM/DD/YY) ORIGINATOR REVIEWER APPROVER

FINAL REPORT 05/04/17 KMACKAY CBUDDEN KOLSON

Line 21 Segment Replacement

Horizontal Directional Drill Technical Feasibility Report

Enbridge Pipelines (NW) Inc.

AFE: 20008211(LYN)

A6JJ-348-95-RP-001

Enbridge Pipelines (NW) Inc. Line 21 Segment Replacment Project Hearing MH-001-2017 File OF-Fac-Oil-E101-2017-07 01

Horizontal Directional Drill Feasibility Report Filed May 8, 2017

of 45

HDD FEASIBILITY REPORT II

Table of Contents

ABBREVIATIONS: ................................................................................................................................... 1

1 INTRODUCTION ............................................................................................................................. 2

1.1 DEFINITIONS ..................................................................................................................................... 2 1.2 REFERENCE DATA ............................................................................................................................... 3

2 DESIGN PROFILE AND PARAMETERS .............................................................................................. 3

2.1 PIPE PROFILE ..................................................................................................................................... 4 2.2 NORTH ENTRY LAYOUT ....................................................................................................................... 5 2.3 SOUTH EXIT LAYOUT ........................................................................................................................... 5 2.4 PIPE PULLBACK .................................................................................................................................. 6 2.5 TIE‐INS ............................................................................................................................................. 6

3 GEOTECHNICAL DETAILS ................................................................................................................ 7

3.1 SUBSURFACE INVESTIGATION ................................................................................................................ 7 3.2 GEOTECHNICAL FEASIBILITY REPORT ...................................................................................................... 8 3.3 GEOTECHNICAL PROPERTIES ................................................................................................................. 9 3.4 STRESS REGIME ................................................................................................................................. 9

4 FEASIBILITY ASSESSMENT ............................................................................................................ 10

4.1 NO‐DRILL ZONE FOR STABILITY ........................................................................................................... 11 4.2 GEOTECHNICAL CONSIDERATIONS ....................................................................................................... 11 4.3 MULTIPLE ATTEMPTS BEING REQUIRED ................................................................................................ 11 4.4 STRAIGHT HOLE ............................................................................................................................... 12 4.5 COBBLES AND BOULDERS ................................................................................................................... 12 4.6 WASHING OF SATURATED SANDS ........................................................................................................ 13 4.7 HDD SOUTH HOLE STABILITY ............................................................................................................. 13 4.8 BEDROCK/OVERBURDEN CONTACT ...................................................................................................... 14 4.9 STEERING & INTERSECT ISSUES ........................................................................................................... 14 4.10 DRILL PATH CONSTRAINTS ................................................................................................................. 15 4.11 HIGHLY FRACTURED SHALE BEDROCK – NORTH TANGENT ........................................................................ 15 4.12 HIGHLY FRACTURED SHALE BEDROCK – HORIZONTAL DRILL PATH ............................................................. 15 4.13 CLEARING OF CUTTINGS FROM HOLE AND HOLE STABILITY ....................................................................... 15 4.14 SPACING......................................................................................................................................... 16 4.15 CONTINGENCY PLANNING – MUD LEAKAGE DETECTION .......................................................................... 16 4.16 DOWNHOLE MONITORING OF MUD PRESSURES ..................................................................................... 16

5 DRILLING SCHEDULE .................................................................................................................... 16

6 STRESS ANALYSIS ........................................................................................................................ 17

6.1 PULL FORCE AND INSTALLATION STRESS ................................................................................................ 17 6.2 PULLBACK AND LIFTING ..................................................................................................................... 18 6.3 OPERATING STRESS ANALYSIS ............................................................................................................. 18

7 HYDRAULIC FRACTURE ANALYSIS ................................................................................................ 18

7.1 HYDROFRACTURE DESIGN CURVE DISCUSSION ....................................................................................... 18 7.2 NO‐DRILL ZONE ............................................................................................................................... 20

8 CONCLUSION .............................................................................................................................. 22

9 REFERENCES ................................................................................................................................ 22



of 45

HDD FEASIBILITY REPORT III

10 APPENDICES ................................................................................................................................ 24

10.1 APPENDIX 1: PROPOSED HDD CROSSING METHOD ................................................................................ 24 10.2 APPENDIX 2: NORTH WORK SITE LAYOUT ............................................................................................. 24 10.3 APPENDIX 3: SOUTH WORK SITE LAYOUT ............................................................................................. 24 10.4 APPENDIX 4: PULL FORCE AND INSTALLATION STRESS ANALYSIS ................................................................ 24 10.5 APPENDIX 5: OPERATING STRESS ANALYSIS ........................................................................................... 24 10.6 APPENDIX 6: HYDROFRACTURE ANALYSIS ............................................................................................. 24 10.7 APPENDIX 7: PULLBACK AND LIFTING STRESS ANALYSIS ........................................................................... 24

Table of Tables

TABLE 1 – PROPOSED LINE 21 SEGMENT REPLACEMENT HDD DETAILS ..................................................................... 2 TABLE 2 ‐ PROPOSED DRILL PATH DETAILS ........................................................................................................... 5 TABLE 3 ‐ ASSUMED GEOTECHNICAL PROPERTIES FOR HYDRAULIC FRACTURE ANALYSIS ................................................ 9 TABLE 4 – PULL FORCE CALCULATION MUD AND SOIL PROPERTIES ......................................................................... 17 TABLE 5 – INSTALLATION OPTIONS ................................................................................................................... 17

Table of Figures FIGURE 1 – OVERVIEW OF LINE 21 SEGMENT REPLACEMENT HDD CROSSING ............................................................ 4 FIGURE 2 – 2017 BOREHOLE LOCATIONS ............................................................................................................ 8 FIGURE 3 ‐ STRESS MAP AND ORIENTATION OF MAXIMUM HORIZONTAL COMPRESSIONAL STRESS (SHMAX) ................. 10 FIGURE 4 ‐ SLOPE STABILITY MODEL TO ASSESS POSSIBLE BLOCK FAILURE UNDER UNDRAINED CONDITION ........................ 21 FIGURE 5 ‐ SLOPE STABILITY MODEL TO ASSESS POSSIBLE BLOCK FAILURE UNDER DRAINED CONDITION ............................ 22 FIGURE 6 ‐ PROPOSED HDD CROSSING METHOD ................................................................................................ 26 FIGURE 7 ‐ NORTH WORK SITE LAYOUT ............................................................................................................. 28 FIGURE 8 ‐ SOUTH WORK SITE LAYOUT ............................................................................................................. 30 FIGURE 9 ‐ HYDROFRACTURE PRESSURE CURVES FOR INTERSECT DRILL .................................................................... 37 FIGURE 10 ‐ PULLBACK OVERBEND FEA STRESS RESULT ....................................................................................... 40 FIGURE 11 ‐ PULLBACK OVERBEND FEA STRAIN RESULT ....................................................................................... 41 FIGURE 12 ‐ PULLBACK HORIZONTAL BEND FORCE FEA RESULT ............................................................................. 42



of 45

HDD FEASIBILITY REPORT 1

Abbreviations:

ARO : Abrasion Resistant Overcoat

CSA : Canadian Standards Association

ERT : Electrical Resistivity Tomography

EFRD: Emergency Flow Restricting Device

FBE : Fusion Bonded Epoxy

FEA : Finite Element Analysis

GR : Grade

HDD : Horizontal Directional Drill

ILI : In-Line Inspection

Kbpd : Kilo-barrel per day (thousands)

KM : Kilometer Marker

KP : Kilometer Post

m : Meter

NDZ : No-Drill Zone

NEB : National Energy Board

NPS : Nominal Pipe Size

NW : Norman Wells

OD : Outer Diameter

OMM : Operation and Maintenance Manual

ROW : Right-of-Way

SPT : Standard Penetration Test

TWS : Temporary Workspace

YJ : Yellow Jacket Polyethylene Dual Layer Coating



of 45


1 Introduction

This report was prepared by the Fluor Canada Ltd. project team for the Enbridge Line 21 Segment Replacement project.

The purpose of this report is to provide a summary of design considerations and engineering calculations contributing to the technical feasibility of the Mackenzie River Horizontal Directional Drill (hereinafter referred to as “this report”) crossing for the NPS 12 pipeline for Enbridge Pipelines (NW) Inc. (Enbridge) Line 21. The proposed horizontal directional drill (HDD) crossing is expected to be completed between August and November 2017.

This report evaluates the key design and construction considerations to install a replacement section of pipe below the south slope slip plane of the Mackenzie River, extending across the river along the proposed drill path between Enbridge kilometer markers (KM) 528.24 and 530.33.

The proposed Line 21 Segment Replacement HDD coordinates and length details are provided in Table 1 below:

Table 1 – Proposed Line 21 Segment Replacement HDD Details

Northing / Easting (m) – North Entry

Northing / Easting (m) – South Exit

Nearest Community

Horizontal Length (m)

Drill Length (m)

6858923.3 / 596465.3

6856909.1 / 595983.0

Fort Simpson 9 km WNW

2,071 2,124

1.1 Definitions

For the purpose of this report the following definitions apply:

OWNER - (Enbridge) shall mean company or companies for whom the work is being performed;

COMPANY - shall mean agents or representatives for Owner including its engineering agencies, inspectors, and other authorized representatives;

CONTRACTOR – shall mean a company or companies contracted for the project to carry out detailed design or construction, including but not limited to logistics, drilling, civil work;

PROJECT – Line 21 Segment Replacement;

MAY – indicates an optional method;

SHALL – indicates a mandatory requirement; and

SHOULD – indicates a strong recommendation to comply with the requirements of this document.



of 45


1.2 Reference Data

Data used to complete the HDD design and analysis includes the following:

Existing pipeline elevation profile as per the topography, alignment sheets, and modified GEOPIG ILI data from 2016. GEOPIG Data from 2016 was vertically offset 2.62 m downwards to match with the 0.88 m average burial depth at top of slope (KM W530);

Current ground elevation profile collected via bathymetric survey completed by Spectrum XLI, September 2016 for North Slope and River Bed Depth;

Current ground elevation profile collected via LiDAR collected over the south slope, by Eagle Mapping Ltd., June 2016;

Historic borehole logs provided by Enbridge from the following years: 1981, 1983, 2012, 2015, 2016;

Borehole logs drilled in 2017 by AMEC Foster Wheeler (AMEC) as part of the Geotechnical Investigation Report; three (3) boreholes drilled on the south slope, two (2) on the north slope, and two (2) under the Mackenzie River;

Additional Geotechnical Factual data provided in 2017 AMEC Geotechnical Feasibility Report CG 14325, March 2017 and

Laboratory Testing Summary and Results Memo, AMEC Foster Wheeler (additional data to supplement CG 14325), April 2017.

2 Design Profile and Parameters

The purpose of the HDD is to install a replacement segment via horizontal directional drill methods below an identified slip plane on the south bank of the Mackenzie River. Observed movement of the south slope since 1995 with surficial bulge formation in 2011, requires the crossing to be completed beneath an investigated and defined zone of instable movement. A “No-Drill Zone” has been established for the drill path which incorporates AMEC Foster Wheeler defined slope stability criteria and Fluor calculated hydrofracture considerations founded on interpreted soil and rock properties. All soil and rock properties utilized for hydrofracture calculations utilize conservatism to limit the possibility of inadvertent returns. The drill path designated entry location is at the north side of the river and the exit is on the south side, although the use of an intersect drill will likely be utilized with rigs drilling from both sides, intersecting below the river within competent bedrock. The exact location of the intersection will be determined by the drilling contractor, but at this stage it has been engineered to occur approximately equidistant between entry and exit locations. Pullback of the pipe string will occur from south side to north side and tie-ins will be completed with lateral induction bends back to the existing pipeline. Figure 1 shows a general overview of the crossing location.



of 45


Figure 1 – Overview of Line 21 Segment Replacement HDD Crossing

2.1 Pipe Profile

The proposed HDD has a horizontal crossing length of 2071.1 meters (m) and includes a designed 16 degree (°) angle for both north entry and south exit drill plans. The HDD will include entry and exit drills angles into grade, utilization of sagbends to correct angles to achieve horizontal tangents within river for planned intersect. Proposed drill lengths, angles and radii are presented in Table 2 below:



of 45


Table 2 - Proposed Drill Path Details

Section Description Length (meters) Angle

(Degrees) Radius

(meters)

North Tangent (A) 568.6 16 -

North Arc 125.7 - 450

River Tangent 605.4 0 -

South Arc (D) 125.7 - 450

South Tangent (E) 698.1 16 -

The pullback section will be strung and welded south of the exit location to take advantage of the near linear path along the existing ROW. Pullback will occur from the south exit of the HDD path to the north side of the Mackenzie River. The proposed HDD layout is shown in Appendix 1: Proposed HDD Crossing Method.

2.2 North Entry Layout

The north entry is located over 300 m away from north slope Mackenzie River bank however in close proximity to a horizontal bend within the permitted right-of-way. The construction layout and specific entry location was optimized to avoid the bend and potential issues of working overtop of the existing pipeline. The entry location is 10 m west of existing pipe centerline.

The geotechnical assessment of north side entry shows clay-clay (till) until bedrock is encountered at a vertical depth of approximately 14 m. Standard drilling practises will be employed for drill prior to entering bedrock which may include excavation for entry pit or installation of casing until competent bedrock to account for weak overburden. The final direction for safe, effective drilling practices will be at the discretion of the drilling contractor based on field conditions. The entry angle as designed is 16 degrees from horizontal. The engineered north drill has a combined drill path length of 1060 m. This length is subject to change at the discretion of drilling contractor based on final intersect location. The proposed construction layout and north entry details are shown in Appendix 2: North Work Site Layout.

2.3 South Exit Layout

The south exit location will be west of the existing right-of-way and approximately 18 m offset from existing pipe centerline. There is an existing emergency flow restricting device (EFRD) station in close proximity to the exit location, which will be relocated south to improve overall constructability. Please reference Appendix 3: South Work Site Layout for visual representation of EFRD station and planned relocation. This work is anticipated to be completed in advance of the HDD activities. Additional temporary and



of 45


permanent workspace has been requested to accommodate the planned drill path, pullback requirements as well as tie-ins. The geotechnical conditions of concern include cobbles, boulders and sand layers. From the AMEC Geotechnical Feasibility report recommendations, it is identified that downhole steering adjustments within the pilot hole could be required. Mitigations for geotechnical concern areas have been accounted for within design and construction as noted in Section 4. Casing may be required to be installed to account for weak overburden however this requirement will be at the discretion of the drilling contractor based on field conditions.

The replacement pipeline will tie into the existing pipe utilizing induction bends to limit required new easement outside of permitted right-of-way. The exit angle is 16 degrees and includes a 3m pit in the design to reduce the lifting heights during pullback, as described in section 2.4. The engineered south drill has a combined drill path length of 1076 m. This length is subject to change at the discretion of drilling contractor based on final intersect location.

2.4 Pipe Pullback

Due to the exit angle of 16 degrees on the south side, additional temporary workspace is required in order to string the pipe for pullback. As reflected in the pullback plan, preliminary calculations show the need to utilize a 3m pit to create a straight entry tangent. Utilizing a below grade trench creates a lifting scenario which requires eight (8) lifting points (six vertical lifts, two horizontal lifts), with a peak vertical height of 9.0m above grade. Finite element analysis (FEA) has been completed to optimize (minimize) lifting height and minimize equipment needs while remaining within the elastic zone of the pipe steel as per Appendix 7: Pullback and Lifting Stress Analysis.

Due to the horizontal angle of pullback relative to existing right-of-way, horizontal roping will be required to align the pipe string while minimizing temporary workspace needed during installation. To minimize the horizontal loading of the pipe cradles and rollers, a roping radius of 405m was selected and confirmed for loading via FEA as per Appendix 7: Pullback and Lifting Stress Analysis.

Efforts were made to reduce the exit angle and reduce the lifting height. Hydrofracture limits the need to remain under the slip plane, and working space availability were all taken into account to determine the optimal lift plan.

2.5 Tie-ins

After installation of the replacement section by HDD, tie-ins are required to connect the existing pipeline on the north and south sides to the newly installed pipe.

Tie-ins will be achieved through lateral induction bends along the horizontal plane utilizing a 10 x Outside Diameter (10D) design bend radii. This radius will allow future ILI tools to flow without restriction as well as optimize (minimize) permanent easement requirements.

In addition to lateral induction bends, overbend induction bends will also be utilized to align HDD crossing to the depth of cover of existing line. Utilization of



of 45


10 x Outside Diameter (10D) design bend radii was selected based on ILI requirements and to reduce required equipment on site for completion.

3 Geotechnical Details

3.1 Subsurface Investigation

Due to the past slope movement observed on the south side of the Mackenzie River, slope monitoring has been completed to assess the condition of the area. Boreholes were drilled on the south slope in 1975, 1983, 1991, and 2012. All historic borehole log data is shallower than the desired depth of the HDD crossing, hence seven additional boreholes were drilled to determine the subsurface conditions on the south slope, as well as under the Mackenzie River and on the north slope.

Figure 2 outlines the location of each additional borehole drilled by the contractor.

New boreholes were drilled from December 2016 through to February 2017. It was agreed during the field execution that two boreholes (one borehole under the river and one on the north slope) could be eliminated from the program based on available data as collected from first two (2) boreholes as collected on north side as well as ERT results. Two boreholes (BH17-05 and BH17-06) on the south slope were drilled using a sonic rig, which provided limited geotechnical information in relation to field tests and available samples for additional laboratory testing. BH17-04, on the base on the south slope, was drilled by rotary rig and Standard Penetration Test (SPT) was conducted in the borehole with Shelby tube samples taken from shallow depths. Rotary rigs were used to drill all additional boreholes (BH17-01, BH17-03, BH17-08, and BH17-09); however no Shelby tubes were taken for remaining drilling program.



of 45


Figure 2 – 2017 Borehole Locations

Electrical resistivity tomography (ERT) was also completed along the HDD path over the Mackenzie River. This geophysical technique was used to map the subsurface characteristics below the river and along the length of the drill path. The data obtained from the ERT, when combined with the borehole information, gives a good indication of the subsurface conditions.

3.2 Geotechnical Feasibility Report

Upon completion of the field borehole study and analysis by AMEC, a geotechnical feasibility report was provided. Through the use of sonic rig for south slope drilling soil stratigraphy was accomplished with moisture content and atterburg limits determined. All data collected was then interpreted via industry standard of understanding and Fluor geotechnical expertise to develop characteristics for hydrofracture analysis and confirmation of preferred drill path.

BH17-01

BH17-03

BH17-08

BH17-04

BH17-05

BH17-06

BH17-09



of 45


3.3 Geotechnical Properties

Table 3 below presents interpreted geotechnical properties for hydraulic fracture analysis and drill path confirmation. Based on recommendations and field data collected, conservative geotechnical properties were utilized as an additional means of safe design for soil characterization. Chainage as listed below follows the drill path from south exit point to north entry point as included within Appendix 1: Proposed HDD Crossing Method.

Table 3 - Assumed Geotechnical Properties for Hydraulic Fracture Analysis

Unit Chainage from South Exit Point (m)

γ Cu φ ν G σt,rm

kN/m3 kPa deg. MPa kPa

Clay 0‐150 19‐20 50 25‐28 1.5‐3

Silt and Sand (Till) 150‐240 20‐21 >200 35‐40 20‐30

Silt (Till) 240‐300 20‐21 >200 30‐35 18‐30

Clay Till 300‐360 20‐21 >200 30‐35 18‐25

Sand 360‐390 20‐21 28‐30 5‐7

Silt (Till) 390‐560 20‐21 >200 30‐35 18‐30

Clay Till 560‐670 20‐21 >200 30‐35 15‐25

Weak Shale 670‐850 22‐24 0.3 38‐215 0‐4

Shale 850‐1790 24‐25 0.25 720‐3,900 18‐240

Weak Shale 1790‐2080 22‐24 0.3 38‐215 0‐4

Clay 2080‐2100 20‐21 >200 28‐30 15‐20

Clay Till 2100‐2110 19‐20 >200 30‐35 15‐20

Cobble 2110‐2124 20‐22 35‐40 35‐70

Undrained shear strength was determined based on either an SPT N-Index or a soil consistency description provided in the borehole logs. Friction angle of granular materials was ascertained from AMEC visual observation during the geotechnical investigation. Rock mass properties were calculated indirectly using equations provided by industry standard Hoek and Brown. As most strength properties are based on indirect approaches or field soil description, any geotechnical calculations using these properties are subjected to uncertainties associated with them.

3.4 Stress Regime

An important parameter that plays a critical role in stability analysis is the ratio of horizontal to vertical stress, known as the K value. In general, depending on



of 45


stress history and plate tectonics of an area, the K value varies from 0.3 to more than 10. According to the World Stress Map (WSM) as shown in Figure 3, the maximum horizontal stress in the area has a NE-SW direction, perpendicular to Rocky Mountains and Mackenzie River in the area. The stress regime on the area is thrust folding such that SHmax > Shmin > Sv where SHmax is maximum horizontal stress, Shmin is minimum horizontal stress and Sv is vertical stress. A magnitude of 5-7 was mentioned on the WSM for the area close the to the project location on the east side of Thundercloud Peak. However, most measured horizontal to vertical stress ratios within bedrock deeper than 130 m in Canada are between 1.2 and 2.6, as discussed by Hoek and Brown. As the drilling path is not completely aligned with principal stresses, the average of maximum and minimum horizontal stress can be considered as horizontal stress for borehole stability and hydraulic fracture design. The overburden pressure is considered as vertical stress.

For this project, horizontal to vertical stress ratios of 1.0, 1.5 and 2.0 were considered for stability analyses.

Figure 3 - Stress Map and Orientation of Maximum Horizontal Compressional Stress (SHmax)

4 Feasibility Assessment

The feasibility of any HDD is dependent on the subsurface conditions encountered. The focus of the feasibility assessment is to establish design and construction strategies to successfully manage those conditions and improve probability of project success. Presented within this report are the engineering criteria, data and analysis results for establishing the proposed drill path for this project. Please reference Enbridge selected Drilling Contractor Execution Plan for additional details related to construction activities.

Assessment of the subsurface conditions is reliant on location of boreholes drilled, quality of lab testing completed on the borehole samples and geotechnical interpretation of the data combined with the ERT provided. The proposed drill path has been chosen based on geotechnical interpretation, location of the slope stability no-drill zone, hydrofracture criteria and mechanical pipe properties. Per the AMEC “Geotechnical Report on Proposed Directionally Drilled Crossing, KP529 Enbridge Line 21”, the drill



of 45


path has a number of potential geotechnical issues that could impact overall feasibility of the project. Utilizing the AMEC information and additional design data, detailed constructability and design reviews have been completed including experienced geotechnical engineering, pipeline engineering, experienced drilling contractor and environmental representatives to review all identified issues and ensure mitigations are available for identified concerns. Based on those reviews, there are no specific hazards that would be considered abnormal or unmanageable in terms of ensuring overall feasibility of the HDD program. Specific risks from Section 4.3 of the AMEC report are listed below along with consideration of risk level and mitigations that have been identified to improve feasibility where necessary.

4.1 No-Drill Zone for Stability

As noted in AMEC Report (CG14325) within section 4.2.1, avoidance is paramount for location of translational slide as identified. Fluor has designed the proposed drill path to provide a minimum spacing of 11 m below defined conservative slip plane. This additional separation will provide additional means of safety from indirect effects in a situation of slope failure.

4.2 Geotechnical Considerations

As noted in AMEC Report (CG14325) within section 4.2.2, two keys parameters were listed as recommendations for final hydrofracture analysis including zero tensile stress to resist leakage and no permeable fractures, or formations to provide direct flow migration to surface. In design the following was considered:

Planned drill path deviations will generally be preferred to be below or lateral to the planned path to avoid reducing the effective overburden thereby eliminating any reduction in defined overburden limiting pressure.

No direct flow migration to surface was indirectly considered in design as it provided confidence that drilling mud pressures could affect plastic zone of overburden but that no mud leakage could reach surface. This does not affect the feasibility of construction.

4.3 Multiple Attempts Being Required

This AMEC specified risk relates to the potential need for multiple drilling attempts as dictated by specific ground conditions during construction. This is not so much a risk associated with drilling feasibility as it is a proposed mitigation to manage difficult drilling conditions. In terms of impact on feasibility, “multiple attempts” should not be interpreted as multiple new entry/exit locations being required to find a successful drill path, but downhole steering changes that may be required to deviate from the engineered drill path. The most significant geotechnical factor that could cause this are the cobbles and boulders identified in the AMEC report. Given the erratic nature of size, distribution, hardness and position of existing cobbles and boulders, until the drill is started it is not possible to identify exactly how this risk would manifest. In terms of mitigations included in the design and construction plans, the ability



of 45


to make steering changes is a key factor in ensuring project success. For this drill the following strategies are being implemented to manage this issue:

Modification of the drill path shall follow the tolerances as listed within Enbridge Standard PCS-006 Horizontal Directional Drill Table 8.1. This tolerance criterion is standard in industry and provides contractor with correction alternatives for drilling operation. If the drill is either directed off course, or a conscious decision is made to modify the drill path due to an issue experienced, proper technical reviews will be completed to ensure the modified drill path is both geotechnically and mechanically acceptable.

Utilizing a mud motor in lieu of jetting assembly in areas of difficult terrain would provide enhanced directional accuracy.

Planned drill path deviations will generally be preferred to be below or lateral to the planned path to avoid reducing the effective overburden.

These mitigations are very typical to drilling operations and should not be considered risks to completion of the project when guided by experienced drilling operators.

4.4 Straight Hole

The drill path is planned to be as straight as possible in consideration of mechanical and geotechnical considerations. It is understood that some downhole steering adjustments are likely and the execution specifications being applied provide tolerances for these adjustments.

4.5 Cobbles and Boulders

Relatively thin cobble layers were encountered in boreholes drilled on the south slope and, in general, cobbles and boulders appear present in many areas beneath the Mackenzie River and within the buried valley.

There is a potential, depending on cobble/boulder size and strength, that the pilot drill may be deflected from the desired drill path. A uniaxial compressive strength of 146 MPa was measured for a boulder at a depth of 28.3 m in borehole BH17-08 (50m south of Mackenzie River centerline). Cobbles and boulders over 0.5 m in diameter with high strength are expected, and planned for, during HDD drilling. Any deflection from the intended drill path requires correction while maintaining permissible bend radii to avoid overstressing the pipe. Deflection may also occur when the drill passes from a soft and loose material to a hard material, like soil to rock. This rock-soil interface is expected to be crossed at a point under the south bank of the Mackenzie River, as the HDD passes from a clay (till) to low-strength shale. The drill path has been designed to ensure the rock-soil interface is crossed as close to perpendicular as possible to limit anticipated deflection. This design is expected to improve the feasibility of remaining along the design profile.

As stated in Section 4.1, it is impossible to determine exactly where or how the drill may interact with a subterranean boulder or cobble. It is not uncommon, however, for HDDs to have this issue. Capable, experienced drilling



of 45


contractors should be able to successfully mitigate this issue. Other specific risks identified in the AMEC along with mitigations include:

Large boulders falling into the hole, blocking the drill path. Given the relatively small diameter (18 inches) of the HDD bore, along with clays and tills being generally stiff, the cobbles and boulders are expected to remain within the soil matrix. Any material that may affect alignment will be broken up by the bit, mud motor and reamer. The hole will also be swabbed as required to ensure the path stays clean and clear of obstructions.

Boulders scratching the pipe. Abrasion resistant overcoating is being used on the pipe specifically to improve the pipe’s ability to resist damage during installation. Application of this coating is standard for HDD installations and has proven to be effective. In addition, final bore diameter shall be 1.5 x outside diameter (OD) of the product pipe with a cleanout reamer pass completed prior to pullback which will provide sufficient clearance to mitigate concerns of pipe-wall interaction.

Boulders increasing tool wear. This is not an issue that reduces project feasibility, but may impact the drilling contractor in terms of the types and number of tools they require or duration of the project. All technical information is being provided to the drilling contractor well in advance of project execution to allow for adequate planning. In normal conditions the reamers are run according to manufacturer’s recommendations and are replaced as required during the reaming process.

4.6 Washing of Saturated Sands

The AMEC report identified loose, saturated sands on the south slope in boreholes BH17-04 and BH17-06 at elevations of 70-80 m.a.s.l. The designed drill path does not traverse either of these areas at stated elevations of concern. As identified BH17-05 is a saturated sand seam. This sand seam being intersected is estimated to be 40m long. There are no other areas along the designed drill path where risks specifically associated with sands are identified.

Sand seams are not uncommon for directional drilling and utilizing an experienced contractor that understands how to manage speed and directional control is the best mitigation. A proper engineered drilling fluid program ensures pressure is applied on the formation which tends to prevent sloughing sands and provides stability. For the designed drill path, in consideration of the geotechnical borehole data collected, project drilling risks associated with sand washout is considered low, but has been accounted for.

4.7 HDD South Hole Stability

The elevation difference between the north entry and south exit locations can cause issues due to potential sloughing of the silt and clay above entry point. This is not expected to be a major issue as the small size of ream will not disturb the formation and the stability of the clay and silt is considered high in this area in comparison to the sand at the lower elevation. Mud settling in the drill path could cause the top 30m of the south entry to empty, leaving the drill path unsupported.



of 45


The best mitigation against this is the installation of casing to provide hole stability. The design package considers installation of casing, but actual application of casing, or any other mitigations deemed necessary for this issue, will be determined between engineering and construction as strategies are finalized. With respect to gas, this would be managed with mud pressure and casing if deemed necessary, but this is a constructability issue that does not a risk in terms of project success.

4.8 Bedrock/Overburden Contact

The risk identified in the AMEC report is associated with the bedrock/overburden interface area on the south approach slope. The drill path will cross this region at a depth of about 115m below grade just prior to a directional changing via sag bend. The issues identified here are very similar to those as noted above in Section 4.2 regarding boulders and cobbles. Given the region is an infilled valley with bedrock anticipated to be weathered and fractured, similar issues with steerability and the potential circulation loss have been considered. The specific design considerations included are:

The drill path is designed to provide a straight path entry into the bedrock/overburden interface area. This will improve steerability and circulation by reducing annular pressure drop.

The hydrofracture calculations have been completed assuming conservative overburden strength properties, which results in the drill path being deeper. Although some loss of circulation into the overburden material may occur, there is a very low risk of inadvertent returns to ground surface or Mackenzie River due to the depth of the drill path being 115m below ground level. Total circulation loss is not likely, given the spaces between the fractured material is anticipated to be infilled with overburden colluvium, but some circulation loss could occur as the drill travels through this region. This would result in additional water and bentonite make up, but is not viewed as a significant risk to project execution or environmental consequences.

Drill tool selection will mitigate significant issues encountered between the bedrock/overburden interface (soft to hard formation). Based on identified geotechnical properties, the expected difference is strengths at depth are expected to minimal.

For construction, the same mitigations would be utilized for this risk as those identified in Section 4.2.

4.9 Steering & Intersect Issues

If an intersection drill is completed, this AMEC consideration recommends ensuring the intersect location is not near the bedrock/overburden interface area due to potential steerability and soil stability issues in this region. Although the exact location of intersect will be at the discretion of the drilling contractor, the design drawings have been designed assuming intersect roughly 300-400m north of the bedrock/overburden interface location. Exact location of intersect will be determined during construction, but staying away from the interface region will



of 45


be a key factor due to the potential steerability and soil stability concerns. Within the North American HDD industry, all intersect drills attempted have been successful to date. Actual intersect will be completed in an area that will maximize success, which will be into competent bedrock under the river. History of intersect drills have shown they have a very high probability of success.

4.10 Drill Path Constraints

The drill path is designed to limit required additional permanent easement both on grade as well as within the Mackenzie River however allowing horizontal directional deflections as required to mitigate any of the previously noted considerations. Current drill path as shown in Overview Map drawing has been designed to allow drill path tolerances within reason, while still remaining well within the requested permanent easement boundaries as submitted to the Government of Northwest Territories.

As geotechnical data collected (borehole and ERT) provide details along a very narrow width, industry assumes that soil stratigraphy and geotechnical concerns are similar along a reasonable width from field data locations as collected.

Based on design and constructability reviews, the drill path and requested permanent easement provide suitable boundaries for successful drill. If significant boulders are encountered and lateral correction is needed which place the final drill path outside of requested boundaries, this will be a requirement of Enbridge to acquire additional agreements with government parties. In addition proper technical reviews will be completed to ensure the modified drill path is both geotechnically and mechanically acceptable.

4.11 Highly Fractured Shale Bedrock – North Tangent

Similar fractured shale concerns as identified in Section 4.5 are anticipated on the north side of the river. The design has considered low RQD values in the upper shale layer. Consideration has been given to the need for casing and has been identified on the project design drawings. The contractor will account for potential casing installation during construction planned and install as necessary.

4.12 Highly Fractured Shale Bedrock – Horizontal Drill Path

Similar issues from Section 4.5 and 4.8 are present here. Since the time the AMEC Geotechnical Feasibility report was completed, the drill path has been lowered to provide better hydrofracture protection. Given the risks of fractured bedrock increase with shallower drill paths, the revised drill path will reduce this risk and improve drilling feasibility. In addition, it is not expected that the fractured bedrock will impact the HDD significantly because of the small ream size and the ability for the rock reamers to break up any debris in the borehole.

4.13 Clearing of Cuttings from Hole and Hole Stability

This risk relates to drilling issues caused by not clearing the drill path and cuttings hydrating into a material that can be difficult to remove. The drilling



of 45


contractor for this project is highly experienced and is aware of the issues related to not properly clearing hole cuttings. Proper drilling fluids program as presented by drilling contractor including details related to swabbing the drill path to keep it clear of cuttings, will mitigate this concern.

4.14 Spacing

This item in the AMEC report covers the need to maintain spacing between the existing pipeline and the drilling equipment to avoid impacting the existing pipeline. The existing pipeline is currently shut down and drained at present, and as such will mitigate any risks for safe work overtop of existing lines. This risk is considered low as detailed construction planning has taken place to ensure spacing for all construction activities has been accounted for and risks to the existing pipeline are minimized. This will include use of rig mats overtop of existing lines in locations were vertical loading on pipe due to equipment loads are expected.

4.15 Contingency Planning – Mud Leakage Detection

This risk relates to the ability to identify and manage inadvertent returns during drilling. Standard industry preventative measures have been considered in engineering design of HDD crossing including but not limited to; annular pressure, volume tracking and monitoring measures. Although the construction contractor will establish detailed execution and environmental management plans, some of the items to be utilized include:

Walks over the drill path to look for visual indications of mud loss Unmanned Aerial Vehicle (UAV) flyovers of drill path to provide broader,

overhead views of the area Turbidity monitoring in the river to look for changes during drilling

operations The environmental management plans will provide details on how the project will manage inadvertent return issues.

4.16 Downhole Monitoring of Mud Pressures

Downhole mud pressure monitoring will be utilized by the drilling contractor. Additional details related to downhole monitoring shall be as per HDD contractor detailed execution plan. This is not considered as a risk to project success as the requirement to monitor mud pressures is standard practice to control hydrofracture limits.

5 Drilling Schedule

Construction of the 323.9 mm OD (NPS 12) pipe crossing may require a drilling schedule of up to 4 months (assumed 12 hour shifts). Due to the anticipated hard rock drilling and the potential for casing on either side, HDD construction activities will include clearing, grading, mobilization, casing installation, pilot hole drilling, reaming, product pipe pull, and demobilization.



of 45


6 Stress Analysis

6.1 Pull Force and Installation Stress

The method implemented to calculate pull forces and installation stress follows PRCI Report PR-227-9424 – Installation of Pipelines by Horizontal Directional Drilling. This method involves splitting the pipe profile into a series of segments to analyse. The five segments used in this report are the north tangent, north arc, straight pipe, south arc, and south tangent sections outlined as sections A – E in HDD Crossing Method drawing D-21-5.8-21743-345LYN. The loads acting on each section are determined in order to calculate the tensile stresses on the pipe. Based on the calculated tensile loads, the pull force required to install the pipe can be determined.

Inputs used to calculate pull forces include pulling tension, pipe diameter, and pressure on the pipe from the drilling mud. Note that point loads due to subsurface conditions such as boulders are not taken into account and may have a significant impact on the pipe.

Assumptions with respect to the drilling fluid have been made as per recommended values provided by PRCI Report PR-227-9424. The assumed properties are outline in Table 4.

Table 4 – Pull Force Calculation Mud and Soil Properties

Mud and Soil Properties

Mud Weight [kN/m3] 11.6

Soil Friction Coefficient 0.3

Fluid Drag Coefficient [kPa] 0.34

Multiple options were considered for the installation of the pipe. The options involve differing entry angles on each slope and are specified in Table 5.

Table 5 – Installation Options

South Entry Angle (°) North Entry Angle (°)

Option 1 12 16

Option 2 12 12

Option 3 14 14

Option 4 16 16

After an assessment of the installation stresses, stresses and costs associated with pipe lifting as well as minimizing additional permanent easement acquisition, it was determined that Option 4 was the preferred installation method. The pull force and installation stress analysis for Option 4 is found in Appendix 7: Pullback and Lifting Stress Analysis of this report.



of 45


6.2 Pullback and Lifting

The pullback and lifting plan is affected by the exit angle on the south side of the Mackenzie River. The pullback process for the pipe is designed to reduce lifting height and to avoid the need for special lifting equipment. In order to optimize the lifting procedure, a pit can be dug to begin lifting at a lower height, reducing the overall height of the lift. Finite Element Analysis (FEA) using Dassault Systemes Abaqus was completed for the HDD lifting procedure in order to determine the minimum allowable bend radius while being lifted. Details from this analysis are outlined in Appendix 7: Pullback and Lifting Stress Analysis.

6.3 Operating Stress Analysis

A pipeline installed by HDD will be subject to similar operating loads as one installed using conventional methods. The pipe will experience expansion loads, internal and external pressure, sustained loading, and elastic bending. The operating loads experienced by the pipeline are discussed in PRCI Report PR-227-9424.

Unlike a conventionally installed pipeline, a pipe installed by HDD will contain only elastic bends along the drill path. This differs from a traditional installed pipe laid in the ground, as cold bends and induction bends are not used. Thus, a flexural analysis must be completed to verify the stresses along the length of the pipeline. Appendix 5: Operating Stress Analysis outlines the elastic bending, hoop stress, and longitudinal stress results which the pipeline is expected to undergo.

An analysis was completed to ensure the specified grade and wall thickness of the replacement pipe used to complete the crossing was acceptable when subjected to the expected operating conditions. Appendix 5: Operating Stress Analysis contains the inputs and results of these calculations.

7 Hydraulic Fracture Analysis

7.1 Hydrofracture Design Curve Discussion

The hydraulic fracture (hydrofracture) design curves for the expected subsurface conditions are shown in Appendix 6: Hydrofracture Analysis. These curves indicate the maximum and minimum drilling pressure to minimize the risk of inadvertent fluid returns based on the anticipated drilling depths and soil conditions. It is typical for this design curve to be used by the drilling contractor to develop a basis for an annular pressure model using the drilling parameters proposed. This annular pressure model will be used in conjunction with the required annular pressure monitoring tool to control the potential for inadvertent drilling fluid returns and loss of drilling fluid circulation.

Three equations were investigated to determine the limiting drilling pressure. Equations include the Delft Equation (Equation 1), which is widely used in industry, the Queen’s Equation (Equations 2a and 2b), and the Kirsch Equation (Equation 3). The Delft and Queen’s Equations both are suitable in the situation



of 45


where the material surrounding the pipe is soil, whereas the Kirsch Equation can be considered when boring in rock formations. Therefore, in locations on the drill path in which the pipe passes through bedrock, the Kirsch Equation will be used to determine the limiting drilling pressure.

Delft Equation

1 .

.,

. .… . . … Equation1

Queen’s Equation

3 12

ln,

whereK 1 …… Equation2 a

32

ln,

whereK 1 …… . . Equation2 b

Kirsch Equation

2 1 1 2 1 ………………………… . . … . Equation3 Where:

Plim Limiting drilling pressure u Water pressure σo Initial ground stress K Horizontal to vertical stress ratio c Soil cohesion cu Undrained shear strength of soil φ Friction angle G Shear modulus ν Poisson’s ratio σt Tensile strength Ro Initial borehole radius Rp,max Maximum radius of plastic zone α Biot coefficient (= 1.0)

One major difference between the Delft and other equations is that the Delft Equation does not include anisotropic ground stress conditions where vertical and horizontal stresses are not equal. In addition, the Delft Equation assumes the soil surrounding the pipe is in a state of shear failure. These two assumptions cause the Delft Equation to provide a non-conservative estimate of the limiting downhole mud pressure. As vertical and horizontal stresses are most likely not equal under the Mackenzie River, the Queen’s Equation provides a more realistic limiting pressure for the south slope of the drill in soil



of 45


under undrained conditions. The Queen’s Equation takes into account the stress ratio and also assumes undrained conditions. The stress ratio has a large effect on both the Queen’s and Kirsch equations. An analysis on the curves at coefficient of lateral earth pressures of 1, 1.5, and 2 were completed, as discussed in Section 3.4. Previous research in the Mackenzie River area indicates that the stress ratio is likely greater than 1, hence it was determined that a value of 2 was the worst case feasible option. Calculations were completed assuming this value.

In general, two approaches are considered to model rock formations. For the first approach, the behavior of discontinuities and intact rock are considered separately. This is suitable for rock formations with relatively few discontinuities. In the other approach, where a rock formation is quite fractured and the size of blocks between discontinuities is relatively small, the rocky formation is modeled as a rock mass with equivalent properties. Since available geotechnical information are not suitable to model the behavior of intact rock and discontinuities, the second approach is considered to model rock formations. In addition, AMEC has not identified any high permeability fracture, faults or formations providing a direct mud flow path from the drilling hole toward the river or ground surface.

When drilling in rock, the Kirsch Equation is used to calculate the maximum tangential stress around the borehole. The equation is based on a closed form solution under elastic condition for an equivalent rock mass and does not consider the plastic behavior of surrounding material. In fact, the Kirsch Equation calculates the pressure that initiates plastic deformation. A detailed numerical analysis can show elastic-plastic behavior of surrounding materials. However, as limited geotechnical laboratory result properties are available, most of the required properties for numerical analysis were estimated indirectly from other available properties. This approach provides a wide range for rock mass properties that are not suitable for detailed numerical analysis. Assuming the tensile strength of a surrounding formation is zero, tensile failure occurs when tangential stress reduces to zero. This was a design consideration as recommended by AMEC and incorporated within design to mitigate over-estimate of rock strength.

A discussion of the hydrofracture curves is included in Appendix 6: Hydrofracture Analysis.

7.2 No-Drill Zone

The hydraulic fracture analysis provides a basis to determine the limiting pressure along the drill path. By comparing this pressure with the maximum and minimum drilling pressures required, a no-drill zone was established based on hydrofracture concerns. The hydrofracture no-drill zone has been combined with the geotechnical no-drill zone provided in the AMEC geotechnical feasibility report to determine an overall no-drill zone. The no-drill zone is displayed in the Appendix 1: Proposed HDD Crossing Method.

The hydrofracture no-drill zone assumes drilling occurs at maximum drilling pressure (20% higher than the minimum drilling pressure). As noted in the drawing D-21-5.8-21743-345LYN, there is a region along the south edge of the



of 45


Mackenzie River were a decreased height of overburden above the pipe occurs which required additional depth of drill to account for hydrofracture requirements. It should be noted that as per AMEC geotechnical feasibility report, inadvertent drilling fluid returns are not expected to rise to ground surface or into the Mackenzie River directly through any high permeable fractures, faults or formation.

A supplementary slope stability analysis was carried out using GeoStudio 2016 ver. 8.16.1.13452 (SlopeW) based on existing geotechnical data to support AMEC no-drill zone identification. The geotechnical properties were interpreted based on lab and field test data. It was also assumed that a thin soft high plastic clay layer exists under the top clay layer that causes block movement toward the Mackenzie River. No deeper slip plane was modeled, however, upon receiving new ground displacement profile from slope inclinometer installed in BH17-05, the model will be revised to reflect possible deep slip plane(s). The main purpose of this modelling is to assess the required setback for south exit point. The analyses were conducted under drained and undrained condition with no seismic loading. As shown in Figure 4 and Figure 5, the south exit point is well beyond the possible block failures with a safety factor of 1.5.

Figure 4 - Slope stability model to assess possible block failure under undrained condition

1.03

0 60 120 180 240 300 360 420 480 540 600 660 720 780

Ele

vatio

n

0

20

40

60

80

100

120

140

160

180

200

220

0

20

40

60

80

100

120

140

160

180

200

220

Color Name Model Unit Weight(kN/m³)

Cohesion(kPa)

Cohesion'(kPa)

Phi'(°)

Clay (Undrained) Undrained (Phi=0) 19 50

Silt and Sand Till (Undrained)

Undrained (Phi=0) 20 200

Silt Till (Undrained)


Clay Till (Undrained)


Sand Mohr-Coulomb 20 0 30

High Plastic Clay Mohr-Coulomb 18 0 11

Bedrock (Shale) Bedrock (Impenetrable)

ClayClay

Sand and Silt Till

Clay Till

Clay Till

Clay Till

Silt Till

Silt Till

Bedrock (Shale)

SandSand

HDD Path

HDD Path

BH17-06BH17-05

BH17-04

Mackenzie River

Enbridge Line 21 - Slope 142 (South Slope)Slope Stability AnalysisUndrained Condition

April 21, 2017

Factor of Safety

≤ 1.00 - 1.101.10 - 1.201.20 - 1.301.30 - 1.401.40 - 1.50≥ 1.50



of 45


Figure 5 - Slope stability model to assess possible block failure under drained condition

8 Conclusion

Due to slope instability on the south slope of Mackenzie River, a horizontal directional drill was deemed the critical crossing means for continued operation of Enbridge Line 21. After completion of 2016/2017 geotechnical field program, a detailed design review and update of the HDD crossing was completed. Presented within this report were expected soil and rock layers during drilling, required hydrofracture drill pressures, stress calculations and mitigation plans to confirm suitable design for successful HDD construction and operation. In addition, section 4 presents detailed mitigation plans and alternatives to address AMEC Foster Wheeler risk considerations. Through detailed engineering including expertise in pipeline and geotechnical design, in collaboration with expertise of an experienced HDD construction contractor, this crossing is determined to have a high level of feasibility with implemented mitigation plans for identified geotechnical and execution risks.

9 References

Mackenzie River South Slope 2014 Geotechnical Report Geotechnical Recommendation for Pipe-Soil Interaction Analysis KP 529.7, Slope 142, Line 21 – Norman Wells to Zama Pipeline, Revision A, CG14302, AMEC Environment and Infrastructure, 9 December 2014

Pipe-Soil Interaction due to Ground Movement Analysis

1.02

0 60 120 180 240 300 360 420 480 540 600 660 720 780

Ele

vatio

n

0

20

40

60

80

100

120

140

160

180

200

220

0

20

40

60

80

100

120

140

160

180

200

220

Color Name Model Unit Weight(kN/m³)

Cohesion'(kPa)

Phi' (°)

PiezometricLine

Clay (Drained) Mohr-Coulomb 19 0 26 1

Silt and Sand Till(Drained)

Mohr-Coulomb 20 0 38 1

Silt Till (Drained) Mohr-Coulomb 20 0 33 1

Clay Till (Drained)

Mohr-Coulomb 20 0 32 1

Sand Mohr-Coulomb 20 0 30 1

High Plastic Clay Mohr-Coulomb 18 0 11 1

Bedrock (Shale) Bedrock (Impenetrable)

1

ClayClay

Sand and Silt Till

Clay Till

Clay Till

Clay Till

Silt Till

Silt Till

Bedrock (Shale)

SandSand

HDD Path

HDD Path

BH17-06BH17-05

BH17-04

Mackenzie River

Enbridge Line 21 - Slope 142 (South Slope)Slope Stability AnalysisDrained Condition

April 21, 2017

Factor of Safety

≤ 1.00 - 1.101.10 - 1.201.20 - 1.301.30 - 1.401.40 - 1.50≥ 1.50



of 45


Structural Impact of Ground Movement at Slope 142 Located at KP 529, M164, C-FER Technologies, February 2015

Remediation Update Mackenzie Riving Crossing, KP 529 Instrumentation Update and Remedial Recommendations, AMEC Foster Wheeler Environment and Infrastructure, 21 May 2016

Installation Stress Calculation Guide

PRCI Report PR-227-9424 – Installation of Pipelines by Horizontal Directional Drilling An Engineering Design Guide, 15 April 1995

Delft Geotechnics Report Technical Report CPAR-GL-98-1 - Installation of Pipelines Beneath Levees Using Horizontal Directional Drilling, Appendix B

Pressure Calculations Technical Specification Horizontal Directional Drilling Under the Freeport, Texas Hurricane Flood Protection System

Mechanics of Hydraulic Fracturing Petroleum Related Rock Mechanics, 2nd Edition, Developments in Petroleum Science 53, Chapter 11, 2008

Horizontal Directional Drilling Design Guideline Pipeline Design for Installation by Horizontal Directional Drilling, Second Edition, ASCE MOP 108, January 2014

AMEC Geotechnical Report Geotechnical Report on Proposed Directionally Drilled Crossing, Mackenzie River Crossing, KP 529 Enbridge Line 21, Final Report, AMEC Foster Wheeler Environment and Infrastructure, 30 March, 2017

Rock Mass Properties Failure Criterion Hoek E, Carranza-Torres CT, Corkum B (2002) Hoek–Brown failure criterion—2002 edition. In: Hammah R, Bawden W, Curran J, Telesnicki M (eds) Proceedings of the Fifth North American Rock Mechanics Symposium (NARMS-TAC), University of Toronto Press, Toronto, pp: 267–273

World Stress Map Heidbach, Oliver; Rajabi, Mojtaba; Reiter, Karsten; Ziegler, Moritz; WSM Team (2016): World Stress Map Database Release 2016. GFZ Data Services.

Trend of Insitu Stress Relationships

Brown E,T, and Hoek E., Trend in Relationships between Measured Insitu Stresses and Depth, International Journal of Rock Mechanics and Mining Science and Geomechanics Abstract, Vol. 15, pp: 211-215.



of 45


10 Appendices

10.1 Appendix 1: Proposed HDD Crossing Method

This Appendix contains the proposed HDD Crossing Method details including Entry and Exit Location, Drill Path details and Annular Pressure Charts.

10.2 Appendix 2: North Work Site Layout

This Appendix contains the North Work Site Layout.

10.3 Appendix 3: South Work Site Layout

This Appendix contains the South Work Site Layout.

10.4 Appendix 4: Pull Force and Installation Stress Analysis

This Appendix contains the input and output values for the pull force and installation stress calculations for all three options outlined in Section 6.1 of this report.

10.5 Appendix 5: Operating Stress Analysis

This Appendix contains the input and output values for the operating stress calculations.

10.6 Appendix 6: Hydrofracture Analysis

This Appendix contains hydrofracture curves for the proposed HDD profile.

10.7 Appendix 7: Pullback and Lifting Stress Analysis

This Appendix contains the details from the FEA Analysis for pullback and lifting.



of 45


Appendix 1: Proposed HDD Crossing Method



of 45


Figure 6 - Proposed HDD Crossing Method



of 45


Appendix 2: North Work Site Layout



of 45

Line 21 Segment Replacement

Documents

Transcript of Line 21 Segment Replacement