NOVA Gas Transmission Ltd. NGTL West Path Delivery 2022 Attachment 6

Desktop Geohazards Preliminary Assessment

Raven River Section ABC Section NOVA Gas Transmission Ltd. Attachment 6 NGTL West Path Delivery 2022 Desktop Geohazards Preliminary Assessment

REPORT Phase I Geologic Hazards Assessment for the Edson Mainline Loop No. 4 Section, ,

Submitted to:

NOVA Gas Transmission Ltd. 450 1 Street SW Calgary, AB T2P 5H1

Submitted by: Golder Associates Ltd. 2800, 700 - 2nd Street S.W., Calgary, Alberta, T2P 2W2, Canada +1 403 299 5600

01189-GAL-C-RP-0002_1

May 26, 2020

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Table of Contents

1.0 INTRODUCTION AND PROJECT LOCATION ...... 1

1.1 Purpose and Scope ...... 1

1.2 Phase I Assessment Summary ...... 2

1.3 Report Structure ...... 3

2.0 PHYSIOGRAPHY AND GEOLOGIC SETTING ...... 3

3.0 METHODOLOGY ...... 3

3.1 General ...... 3

3.2 Development of Hazard Identification and Classification Criteria ...... 4

3.2.1 Landslides ...... 4

3.2.2 Seismic (Ground Shaking) ...... 6

3.2.3 Seismic (Liquefaction) ...... 6

3.2.4 Seismic (Surface Fault Rupture) ...... 8

3.2.5 Subsidence (Karst) ...... 8

3.2.6 Subsidence (Underground Mining) ...... 8

3.2.7 Subsidence (Fluid Withdrawal) ...... 9

3.2.8 Collapsible or Expansive Soils ...... 10

4.0 RESULTS ...... 11

4.1 Landslide Hazards ...... 12

4.2 Seismic Hazards ...... 12

4.3 Subsidence Hazards ...... 13

4.3.1 Karst ...... 13

4.3.2 Underground Mines ...... 14

4.3.3 Fluid Withdrawal...... 14

4.4 Collapsible or Expansive Soils ...... 14

5.0 RECOMMENDATIONS ...... 15

5.1 All Hazards ...... 15

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5.2 Landslide Hazards ...... 15

5.3 Seismic Hazards ...... 15

5.4 Subsidence Hazards ...... 16

5.5 Collapsible or Expansive Soils ...... 16

6.0 CLOSURE ...... 17

7.0 REFERENCES ...... 18

7.1 Alphabetical References ...... 18

7.2 References by Hazard Type ...... 23

TABLES

Table 1 – Edson Mainline Loop No. 4 Raven River Section - Phase I Geologic Hazards Classification Summary

Table 2 – Edson Mainline Loop No. 4 Raven River Section - System Phase I Summary of Hazards

FIGURES Figure 1 – Edson Mainline Loop No. 4 Raven River Section - Overview Map Figure 2 – Edson Mainline Loop No. 4 Raven River Section - Landslide Hazard Areas Figure 3 – Edson Mainline Loop No. 4 Raven River Section - Seismic Hazard Areas (Ground Shaking and Liquefaction) Figure 4 – Edson Mainline Loop No. 4 Raven River Section - Fluid Withdrawal Subsidence Hazard Areas Figure 5 – Edson Mainline Loop No. 4 Raven River Section - Expansive and Collapsible Soils Hazard Areas

APPENDICES Appendix A – Electronic Files

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1.0 INTRODUCTION AND PROJECT LOCATION This report is a summary of the results of a desktop Phase I Geologic Hazards Assessment (Phase I Assessment) conducted by Golder Associates Ltd. (Golder) for the NOVA Gas Transmission Ltd. (NGTL), a wholly owned subsidiary of TransCanada PipeLines Limited (TCPL), an affiliate of TC Energy Corporation, proposed Edson Mainline Loop No. 4 Raven River Section (Project), in Alberta, Canada. We completed this Phase I Assessment in support of the engineering, design and construction of the Project. The proposed pipeline section assessed herein is the approximately 18 kilometres (km) long NPS 48 Edson Mainline Loop No. 4 Raven River Section that will extend from the Schrader Creek East Compressor Station in the south (KP 0+000) to the Clearwater Compressor Station in the north (KP 18+212 in the north), as shown on Figure 1. 1.1 Purpose and Scope The purpose of this Phase I Assessment was to complete a regional-scale identification and assessment of potential geologic hazards that may affect the Project. The geologic hazards assessment is intended to be used by NGTL for development of an inventory of potential geologic hazards that could affect the Project during and after construction, which, in turn, can be used for planning risk management of the system. Additionally, this Phase I Assessment is intended to be used for identification of areas for possible additional investigation to more fully characterize and mitigate geologic hazards in subsequent phases of hazard assessment.

Golder has completed Phase I Assessments in the recent past for the NGTL pipeline system (Golder 2015a, 2016a, 2017, 2018a and 2018b). Because portions of this Project are located adjacent to work previously performed by Golder, we reviewed and incorporated relevant results into this Project.

To carry out the Phase I Assessment, we compiled, reviewed, and analyzed regional-scale maps and reports from public sources, and conducted a remote sensing review of available LiDAR data and aerial imagery. We conducted our assessment along the proposed alignment KMZ files provided by NGTL on February 2, 2020. The proposed pipeline will primarily parallel the existing NGTL Pipelines, which have been previously assessed by Golder (Golder 2015a, 2016a).

No aerial reconnaissance was completed by Golder during this assessment, however a helicopter reconnaissance was completed as part of the 2015 assessment of nearby pipelines. Relevant findings from the 2015 helicopter reconnaissance are included in landslide descriptions in Section 4.1 of this report.

For the purposes of the Phase I Assessment and this report, a geologic hazard is a natural geologic condition, ongoing geologic process, or potential natural event that could adversely affect the construction, operation, or integrity of a pipeline. This report describes the methodologies used for the identification and classification of geologic hazards, the results of the assessment, and recommendations for further work (as appropriate) regarding the various hazards identified.

In conducting the Phase I Assessment, we considered the following hazards for the Project:  unstable slopes, such as landslides and rock falls  seismic hazards, including surface fault rupture, soil liquefaction, and strong ground shaking  ground subsidence associated with underground mines, fluid withdrawal (oil and gas or groundwater), or karst  expansive and collapsible soils

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The list of hazards was specified in our Proposal to NGTL dated January 2020. Our scope of services did not include an assessment of watercourse erosion (hydrotechnical) hazards. For each hazard identified during the Phase I Assessment, we assigned a qualitative hazard classification (low, moderate, or high) based on several criteria, such as the proximity of the potential hazard to the proposed pipeline, the level of activity of the geologic process that results in the potential hazard, the areal extent of the potential hazard, the perceived likelihood of the potential hazard to affect the proposed pipeline during its service life, and the types of the potential consequences of the hazard to the respective pipeline. A summary of the hazard classification criteria is provided in the attached Table 1. The hazard classifications are relative to each individual hazard. For example, a high hazard landslide is not necessarily equivalent in potential severity or likelihood to a high hazard subsidence feature. 1.2 Phase I Assessment Summary Based on the information reviewed for this Phase I Assessment, in general, the potential for geologic hazards to affect the majority of the Project appears to be relatively low. There are localized geographic areas that are more likely to be affected by specific geologic hazards, including landslides, liquefaction, subsidence and collapsible and expansive soils. The results of the Phase I Assessment are summarized below. Landslides Two possible individual landslides are located within 30 m of the proposed pipeline alignment that may pose a hazard to the Project. An additional two landslides were identified more than 30 m from the proposed alignment but within approximately 100 m, and therefore do not meet the classification criteria as low, moderate, or high hazards; however, these are included should an alternate alignment be considered in the future. An additional 154 areas with steep slopes (i.e., areas with slope angles greater than 14 percent [8 degrees]) were classified as low hazard landslide areas. Seismic The Project is located is in an area of apparent low historical earthquake activity, and based on the references reviewed, appears to have a low potential for damage from ground shaking associated with future seismic activity. No active (e.g., Holocene) or potentially active (e.g., Quaternary) faults in the vicinity of the Project were identified in any of the references reviewed for this assessment. One area along the proposed Project pipeline alignment is underlain by surficial deposits potentially susceptible to liquefaction, although based on modeled ground shaking, the potential for the occurrence of soil liquefaction is low. Subsidence The entire Project is underlain by potential subsidence hazards; however, these areas were classified as low hazard areas. These include potential fluid withdrawal-related subsidence hazard areas associated with oil, gas and groundwater extraction from reservoirs and pools underlying the ROW; however, no reports of fluid withdrawal-related subsidence were identified in the region. Based on the references reviewed for this assessment, no underground mining-related subsidence areas or karst-related subsidence areas have been identified. Collapsible or Expansive Soils Based on the references reviewed for the Project, soils along the proposed alignment are not reported to have significant collapsible or expansive properties, and there is no reported damage to structures or infrastructure resulting from collapsible or expansive soils in the region. Approximately 3 km of the alignment, where it is underlain by glaciolacustrine material, is classified as a low hazard area for collapsible or expansive soil.

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1.3 Report Structure The Phase I Assessment report that follows includes the following major elements:  A description of the route followed by the Project, including a general description of the physiographic and geologic conditions traversed by the Project (Section 2).  A summary of the methods used to conduct the Phase I Assessment, including the criteria used to classify the various potential geologic hazards identified during the assessment, and the rationale for the development of the criteria used to identify the potential hazards (Section 3).  A summary of the results of the Phase I Assessment (Section 4).  Recommendations for additional work (as appropriate), based on the results of this assessment (Section 5).  A bibliographic listing of the references that were collected and reviewed to conduct the Phase I Assessment (Section 6).  Electronic files for this project, including a GIS database and KMZ files generated for this project (Appendix A). 2.0 PHYSIOGRAPHY AND GEOLOGIC SETTING The Project is located in Alberta, entirely within the Alberta Plain Division of the southern Interior Plains physiographic region (Natural Resources Canada 2009; Bostock 2014). The southern Interior Plains is covered primarily by Pleistocene glacial sediments. Glacial deposits underlying the Project predominantly consist of glacial till and glaciolacustrine (lake) deposits (Fenton et al. 2013; Klassen 1989). The proposed alignment traverses an undulating to hummocky area with elevations generally between approximately 1,150 meters (m) above mean sea level (amsl) and approximately 1,210 m amsl. The proposed alignment crosses the Raven River at approximately 1,120 m amsl, in an area of fluvial fine sand, silt and clay with minor gravel beds (Boydell et al. 1957). Bedrock underlying the proposed alignment is the Paleocene Paskapoo Formation, a succession of generally flat-lying greyish calcareous sandstones, siltstones and mudstones (Boydell et al. 1974; Prior et al. 2013). Despite the overall low slope angles and low relief across the southern Interior Plains, landslides occur along the sides of valleys where creeks and rivers have incised down into geologic units that are susceptible to landslides. 3.0 METHODOLOGY 3.1 General To complete the Phase I Assessment, Golder relied on a review and analysis of data contained in publicly available, regional-scale maps and reports of geologic conditions and geologic hazards, as well as a geomorphic review and analysis of Google EarthTM and ESRI aerial imagery, orthophotographs supplied by NGTL and 1-metre resolution LiDAR data provided by NGTL via Midwest Survey in February 2020, dated 2015 and 2017. Additional maps and reports were collected from a variety of sources for the assessment, typically from government agencies. Where appropriate, the same resources used for previous NGTL Phase I Assessments were used for this study (Golder 2015a, 2016a, 2017, 2018).

The references acquired and reviewed for the Phase I Assessment are cross-referenced to the relevant hazards for which they were used in Section 6. Note that an individual reference may have been used to assist in delineating several hazard types, depending on the information contained in that reference, and thus may be listed under multiple hazard categories.

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For the geologic hazards reviewed for this assessment, we assigned a relative hazard classification of low, moderate, or high, based on criteria developed to describe the hazard’s severity and the pipeline’s potential exposure to the hazard (Table 1). In general, the hazard classifications assigned for this Phase I Assessment are intended to be consistent with the hazard classifications used for the previous NGTL Phase I Assessments (Golder 2015a, 2016a, 2017, 2018a and 2018b). 3.2 Development of Hazard Identification and Classification Criteria In this section, we discuss the development of criteria, including their rationales, which were used to identify and classify each geologic hazard considered during this assessment. The discussion for each potential hazard also includes a brief description of the nature of the particular hazard and how it may affect a pipeline. Table 1 summarizes the classification criteria, which describes the specific criteria used to classify the various geologic hazards into low, moderate, and high hazard categories. 3.2.1 Landslides A landslide is the “movement of a mass of rock, debris, or earth down a slope,” and encompasses geologic processes such as debris or mud flows, rotational slides (slumps), translational slides, earth flows, rock falls, or debris slides (Cruden 1991; Cruden and Varnes 1996). Landslides can adversely affect pipelines by bending the pipe along the lateral limits or failure planes of the landslide, by compressing and tensioning the pipe during downslope movement of soil and rock, by undercutting and exposing the pipe (in the event that material flows out from underneath the pipeline), or by physically impacting the pipe in the event of a rapid debris flow or rock fall.

As part of this Phase I Assessment, we completed a geomorphic analysis of publicly available Google EarthTM and ESRI aerial imagery, and 2015 and 2017 1-metre resolution LiDAR imagery provided by NGTL. The resolution of our assessment is limited by the resolution of the data available.

We identified potential landslides that were completely or partially within 100 m of the proposed pipeline (i.e., a 200 m-wide corridor centered on the proposed pipeline centerline). That means any landslide that had any part within 100 m of a proposed pipeline was identified and delineated. We have assumed that the constructed right of way (ROW) will be approximately 30 m centered on the proposed pipeline centerline. Thus, we consider landslides located within 15 m of the proposed pipeline alignment to pose a higher hazard/threat both during and post-construction of the pipeline.

Slope inclinations derived from the LiDAR data were also used to evaluate landslide hazards (i.e., slopes greater than 14 percent [8 degrees]); slope inclinations were evaluated for the 200 m-wide corridor, as these may be of interest to NGTL should an alternate alignment be considered in the future.

Sections 7.1 and 7.2 contain a list of the references reviewed to identify landslides and areas prone to landslides. Low Hazard We characterized the following areas and landslide types as low hazards:  Areas with slopes greater than 14 percent (8 degrees) with no mapped landslides.  Shallow, small stream bank slumps between 15 m and 30 m of the pipeline alignment.  Relict landslide that crosses or is within 30 m of the pipeline alignment with low potential for renewed activity.  Apparently dormant landslide between 15 and 30 m of the pipeline alignment.

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 Historical landslides that have been remediated and show no signs of movement post-remediation, that cross or are within 30 m of the pipeline alignment.  Rock fall deposition zones within 30 m of the pipeline alignment but that do not cross the pipeline alignment and where the rock fall source areas are depleted, and the source slopes have stabilized.

Justification: We classified slopes with an inclination greater than 14 percent (8 degrees), but with no mapped landslides as low hazard landslide areas. A threshold of 14 percent slope inclination was used for previous NGTL Phase I Assessments (Golder 2015a, 2016a, 2017, 2018); thus, the same threshold was used in this assessment. We have selected 14 percent as the threshold slope inclination for evaluating terrain for landslide hazards so that the most likely areas for landslide occurrence can be targeted for future LiDAR imagery review, and during future aerial or ground reconnaissance. Landslides, however, may also occur on slopes with an inclination less than 14 percent (8 degrees).

We classified low hazard landslides as including relatively small stream bank rotational, translational, and flow landslides that appeared to be too shallow to affect a pipeline. Although these very shallow slumps may be active landslides, they are unlikely to affect a pipeline unless they significantly expand in depth and/or lateral extent.

In some instances, landslides may have occurred under climatic or topographic conditions that are no longer present, such as the climatic conditions present during the latest Pleistocene and early Holocene (Cruden and Varnes 1996). If a landslide crossed by the pipeline could be clearly identified as relict, the landslide was classified as a low hazard.

Historical landslides that have been remediated are also classified as low hazard landslides.

Finally, rock fall deposition areas where the rock fall source area is depleted, and the source slope has stabilized are classified as low hazard landslides. Moderate Hazard Moderate hazard landslides include the following:  Apparently dormant landslides that cross or are within 15 m of the pipeline alignment.  Apparently or possibly active landslides 15 m and 30 m of the pipeline alignment.  Debris flow run-out (depositional) areas that cross the pipeline alignment.  Rock fall deposition zones within 30 m of the pipeline alignment but that do not cross the pipeline alignment, with active source areas and with potential for future rock deposition across the pipeline alignment.

Justification: If a landslide crossed by or within 15 m of the pipeline alignment could be clearly identified as dormant (i.e., the most recent movement apparently occurring more than 100 years ago) the landslide was classified as a moderate hazard.

We considered the remaining areas described above to have moderate landslide hazards, because they do not currently appear to contain specific, active landslides that intersect the alignment. Therefore, based on the information available to Golder at this time, these areas appear to be a lower threat to the pipeline than high landslide hazard areas. However, moderate landslide hazard areas could be sensitive to disturbance during or after construction (i.e., a landslide could be triggered or reactivated in these areas), and existing landslides in proximity to the alignment could enlarge (such as from landslide retrogression) and intersect the alignment at a future time.

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High Hazard For the purposes of this study, we considered high hazard landslides to be:  Apparently or possibly active landslides that cross or are within 15 m of the pipeline alignment.  Debris flow source areas or debris flow channels that cross the pipeline alignment.  Rock fall deposition zones that cross the pipeline alignment. Justification: Active landslides that cross the pipeline alignment or are located within 15 m of the alignment may have a high potential to adversely affect the pipeline(s), with the apparent potential higher than that for moderate landslide hazard areas. 3.2.2 Seismic (Ground Shaking) Strong ground shaking from large earthquakes can potentially result in wave propagation damage to pipelines, caused by lateral and vertical ground movements, or accelerations (O’Rourke and Liu 1999, 2012). The potential hazard from earthquake wave propagation is commonly measured by the ground shaking parameter of peak horizontal ground acceleration (PGA), expressed as a percentage of the Earth’s gravitational acceleration (g). Earthquake strong ground shaking may also trigger liquefaction, lateral spreading of saturated soil (discussed in Section 3.2.3), and landslides. Sections 7.1 and 7.2 list seismic hazard references consulted for this project.

Based on empirical correlations of observed and reported earthquake shaking damage and corresponding PGAs, along with descriptions of the level of potential damage (Wald et al. 1999), we developed earthquake acceleration thresholds and intervals to characterize low, moderate, and high hazards from potential wave propagation damage due to strong ground shaking. The database for earthquake acceleration used in this Phase I Assessment was the Canadian Geological Survey’s (Halchuk et al. 2015b) acceleration hazard mapping. The PGAs used were for a 10 percent probability of exceedance in a 50-year period, which represents a return period of 475 years.

The assigned earthquake strong ground shaking hazard classification levels, applied from the use of the Canadian Geological Survey’s (Halchuk et al. 2015b) mapping, are:  Low Hazard: <0.15 g  Moderate Hazard: 0.15 g to 0.25 g  High Hazard: >0.25 g Justification: Empirical correlations of potential damage related to PGAs by Wald et al. (1999) indicate that light damage to engineered surface structures generally does not occur until the acceleration range of 0.09 g to 0.18 g. Moderate damage begins to occur in the acceleration range of about 0.18 g to 0.34 g, and moderate to severe damage occurs at accelerations from 0.34 g to 1.24 g and greater. With these data, we conservatively selected the hazard categories listed above to reasonably represent potential low, moderate, and high hazards to a buried pipeline resulting from earthquake shaking. 3.2.3 Seismic (Liquefaction) Liquefaction can occur during strong seismic shaking in saturated (e.g., shallow groundwater) loose cohesionless soils. During strong seismic shaking, pore pressure increases can occur, causing these soils to lose grain-to-grain contact and to develop a slurry-like consistency. Liquefaction can also occur within “sensitive” clay deposits, such as marine deposits of the Champlain Sea (e.g., the Leda Clay), that can undergo a significant loss of shear

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strength when disturbed (Aylsworth et al. 2000; Quinn et al. 2007a, b). Liquefaction can result in settlement or floating (buoyancy) of the pipeline, lateral spreading of the ground containing the pipeline, and slope instability. Lateral spreading is a process whereby liquefied ground cannot support even low to moderate height slopes, and the ground flows, or translates downhill, resulting in large lateral movements and ground cracking.

To assess the potential for soil liquefaction, we assumed that all areas mapped as Holocene alluvium (geologically young [<10,000 years old] sediment deposited by flowing water) or lacustrine sediments (lake bed sediments) were saturated, loose, and composed of potentially liquefiable soil. In addition, marine deposits like those of the Champlain Sea (e.g., the Leda Clay) were also considered susceptible to cyclic softening. References used to map alluvial and lacustrine sediments are presented in Sections 7.1 and 7.2.

We identified and mapped areas that appeared to be underlain by alluvial or lacustrine deposits using a combination of surficial geology maps, topographic maps, LiDAR data, and aerial imagery. In general, we assumed that relatively flat, low-lying areas adjacent to rivers and lakes were underlain by liquefaction susceptible soil, i.e., alluvial or lacustrine deposits. The assumption that alluvial deposits are inherently liquefiable is conservative because the thickness, grain size distribution, and density of the materials in these deposits is not known, the depth to the groundwater table cannot be ascertained accurately from geologic and topographic maps, and these deposits may in fact be unsaturated part or most of a typical year.

To assign a relative hazard classification for liquefaction, we then matched the Geological Survey of Canada’s acceleration hazard mapping for the 475-year return period PGAs (Halchuk et al. 2015b) to the areas mapped as primarily underlain by Holocene alluvial or lacustrine deposits. The probability of a large earthquake in the vicinity of the pipeline alignment appears low. For consistency with other pipelines owned by NGTL, we assigned the hazard classifications as follows:

Low Hazard: The pipeline alignment crosses unconsolidated Holocene sediment primarily consisting of silt to gravel that meets one set of the following criteria:  <0.1 g PGA and zone of alluvium (river or stream) is at least 90 m wide where crossed by the pipeline; or  0.1 g to 0.2 g PGA, groundwater is deeper than about 9 m, and zone of alluvium (river or stream) is at least 90 m wide where crossed by the pipeline.

Moderate Hazard: The pipeline alignment crosses unconsolidated Holocene sediment primarily consisting of silt to gravel that meets one set of the following criteria:  PGAs between 0.1 g and 0.2 g, groundwater less than 9 m deep, and zone of alluvium (river or stream) is at least 90 m wide where crossed by the pipeline; or  PGAs greater than 0.2 g, groundwater between 3 and 9 m deep, and zone of alluvium (river or stream) is at least 90 m wide where crossed by the pipeline.

High Hazard: Pipeline alignment crosses unconsolidated Holocene sediment primarily consisting of silt to gravel that meets the following criteria:  PGAs greater than 0.2 g, groundwater less than 3 m deep, and zone of alluvium (river or stream) is at least 90 m wide where crossed by the pipeline.

Justification: The probability of soil liquefaction can be assessed by considering the susceptibility of the soil to liquefaction (based on such parameters as soil density, cementation, particle size gradation, confining stress, layer thickness, and water content) and the magnitude and duration of shaking for various seismic event

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recurrence intervals (Youd et al. 2001). In the absence of actual soil and groundwater characterization, and in the absence of estimated magnitude, duration, and recurrence intervals of shaking, it was only practical to assign a qualitative soil liquefaction hazard based on interpreted soil type and published PGA levels for a given seismic event (the 475-year recurrence interval event with a probability of exceedance of 10 percent in 50 years). Therefore, while the evaluation of liquefaction hazards is based on scientific fundamentals, the hazards levels are qualitative and specific to this Phase I Assessment.

To assess the relative significance of liquefaction hazards to ground shaking hazards, we assumed that the potential hazard to the pipeline from liquefaction would be greater than that from strong ground shaking from an earthquake. We made this assumption, because most modern ductile, welded steel pipelines perform well under ground shaking conditions, but liquefaction-related phenomena, such as lateral spreading, can create significant permanent ground deformation effects, and thus can induce much greater stress on a pipeline than shaking alone. Therefore, we used slightly lower PGA threshold values to define the low, moderate, and high liquefaction hazard levels than were used to define the strong ground shaking hazard levels. We also considered a depth to groundwater component in assessing liquefaction hazards, because areas with shallow groundwater are more likely to experience liquefaction than those with a deeper groundwater table. 3.2.4 Seismic (Surface Fault Rupture) We assessed potential surface fault rupture hazards primarily by reviewing available literature and mapping concerning the location of active (e.g., Holocene) and potentially active (e.g., Quaternary) faults and seismic zones in Canada. In addition, we reviewed LiDAR data and aerial imagery to identify linear geomorphic features that could be representative of active or potentially active faults. The hazard classifications for surface fault rupture, based on the schema used in previous NGTL Phase I Assessments, are summarized in Table 1. 3.2.5 Subsidence (Karst) Karst is a geological term referring to a type of surface topography that generally forms by the subsurface dissolution of carbonate rocks such as limestone and dolomite, and evaporite rocks such as gypsum and halite (salt)1. Subsidence features in karst topography include sinkholes, surface caves, subsurface voids, and underground bodies of water (Ford 1998). Karst topography represents a potential hazard to pipelines primarily because of the potential for collapse of subsurface voids and the formation of sinkholes at the surface.

We assessed karst subsidence hazards by reviewing previous mapping of bedrock geology, karst-prone areas, and karst features (e.g., sinkholes) compiled by government agencies. No karst-prone bedrock types were found to underlie the assessed alignment (Prior et al. 2013). Sections 7.1 and 7.2 contain lists of references reviewed to evaluate karst hazards. The hazard classifications for karst subsidence, based on the schema used in previous NGTL Phase I Assessments, are summarized in Table 1. 3.2.6 Subsidence (Underground Mining) Collapse or subsidence of underground voids left by underground mining can produce sinkholes or regional subsidence similar to those produced by karst. These sinkholes can result from collapse of overlying overburden into an underground mine cavern/void or the sudden or gradual collapse of the cavern itself (Whyatt and Varley 2008).

1 Karst features that form in gypsum or salt are sometimes referred to as “pseudokarst.” In the strictest definition, karst refers to dissolution of carbonate bedrock such as limestone or dolomite.

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To evaluate potential underground mining subsidence hazards, we relied on GIS-based point and polygon data, spreadsheets of mine locations and maps of underground mining areas. For a list of the references consulted to evaluate underground mine subsidence, see Sections 7.1 and 7.2.

The hazard classifications for potential underground mine-related subsidence, based on the schema used in previous NGTL Phase I Assessments, are summarized in Table 1. 3.2.7 Subsidence (Fluid Withdrawal) Withdrawal of underground fluids such as oil and gas or groundwater can cause subsidence over widespread areas, and localized surface fissuring with differential displacement. Examples of fluid withdrawal subsidence in North America include pumping of oil and gas that has caused up to 9 m of subsidence in Los Angeles County, California, and withdrawal of groundwater that has produced approximately 9 m of subsidence in Mexico City, Mexico and in the San Joaquin Valley of California (Poland 1984; Galloway and Riley 1999). In some instances, subsidence as rapid as 15 centimetres (cm) per year has been recorded in the San Joaquin valley (Galloway and Riley 1999).

Noticeable or measurable fluid withdrawal subsidence occurs through drawdown of underground fluids in combination with geologic conditions favorable to subsidence (Poland 1984). Typically, fluid withdrawal subsidence occurs when the volume of fluids being removed from a subsurface aquifer is greater than the volume of fluids recharging the aquifer, and when soil or bedrock within the aquifer is compressible and consolidation occurs.

In most cases, subsidence from fluid withdrawal is spread over a large area, with little differential movement within the subsiding areas. In some instances, faults or fissures can form in response to fluid withdrawal, but these rarely experience more than 0.3 to 0.6 m of differential movement (Coplin and Galloway 1999; Pavelko et al. 1999). While gravity-dependent utilities, like sewer lines, or rigid structures such as homes or highways, can be damaged or rendered unusable, more flexible and pressurized utilities like natural gas pipelines typically feel little effect because the subsidence is usually spread out over several km and the change in gradient does not affect pressurized systems.

To evaluate potential fluid withdrawal subsidence hazards for the Project we relied on mapped locations of groundwater aquifers and oil and gas well fields and pools. Sections 7.1 and 7.2 contain a list of the references consulted to evaluate fluid withdrawal subsidence.

Our hazard classifications for potential fluid withdrawal subsidence are as follows: Low Hazard Low hazard fluid withdrawal subsidence areas include those where the pipeline alignment crosses areas that contain well fields for oil and gas explorations or areas with major groundwater aquifers, but with no reports of fluid withdrawal-related subsidence.

Justification: Pumping of oil and gas or groundwater from subsurface aquifers is an essential precondition for fluid withdrawal subsidence. However, in most instances, pumping of underground fluids is not associated with noticeable or measurable subsidence because the local geologic conditions are not susceptible to subsidence. We have classified areas with oil and gas well fields or known groundwater aquifers with no reports found of fluid withdrawal subsidence (at the time of this assessment) as low potential fluid withdrawal subsidence hazard areas. While subsidence could potentially occur in these areas, subsidence either is not occurring, is too small in magnitude to have been widely reported or is located in too remote of an area to have been widely noticed.

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Moderate Hazard Moderate hazard fluid withdrawal subsidence areas include those where the pipeline alignment crosses areas that contain oil and gas or groundwater well fields with reports of fluid withdrawal subsidence, but with no reports of damage resulting from this subsidence.

Justification: Areas with known or probable fluid withdrawal subsidence represent areas where this subsidence could potentially affect a pipeline. In densely populated areas, a lack of reports concerning damage resulting from this subsidence could indicate that the subsidence is relatively minor and is unlikely to significantly affect a pipeline. Conversely, in rural or remote areas, a lack of reports concerning damage could simply indicate that the area is too sparsely populated to have experienced widespread damage. We have classified these areas as moderate potential fluid withdrawal subsidence areas because they represent areas where a pipeline could potentially be affected, but the probability does not appear to be as significant as the high potential fluid withdrawal subsidence areas. High Hazard High hazard fluid withdrawal subsidence areas include those where the pipeline alignment crosses areas that contain oil and gas or groundwater well fields that have reported or documented evidence of damaging fluid withdrawal subsidence, such as subsidence that has damaged roads and structures (e.g., roads frequently repaired from subsidence, badly damaged buildings, damaged utilities). High hazard fluid withdrawal subsidence areas also include those where the pipeline alignment crosses areas that have documented evidence of fluid withdrawal subsidence that has resulted in significant differential displacement, such as the formation of fissures or faults.

Justification: High potential fluid withdrawal subsidence hazard areas represent fluid withdrawal subsidence areas most likely to result in damage to a pipeline or associated facilities. While in most instances, fluid withdrawal subsidence is spread over a large area, the formation of features with significant differential displacement (such as fissures and faults), could result in stress on a pipeline. 3.2.8 Collapsible or Expansive Soils Collapsible or expansive soils may experience considerable volume change, usually related to an increase or decrease in water content associated with seasonal changes, or extreme weather events (e.g., drought and storm/flood conditions). In some cases, significant expansion or contraction of a soil can damage buildings and infrastructure.

In the prairie provinces of Canada, soil containing clay minerals derived from erosion of shale formations can often exhibit collapsible or expansive behavior (Hamilton 1980; Agriculture and Agri-Food Canada 1998 and 2015). These clay minerals are commonly found within glacial soils, such as glaciolacustrine deposits and in soils derived from erosion of glacial deposits, such as some alluvial or lacustrine deposits (Hamilton 1980).

Data from Agriculture and Agri-Food Canada (2015) were used to plot and assess the extents of collapsible and expansive soils underlying the Project. Exploratory and reconnaissance Soil Survey reports were reviewed for areas where soil survey data were not available (Peters and Bowser 1957).

Our hazard classifications for collapsible or expansive soils are as follows:

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Low Hazard We classified low hazard collapsible or expansive soil areas along the pipeline alignment where mapped soils are not reported to have significant collapsible or expansive properties, and there is no reported damage to structures or infrastructure.

Justification: A national soil database that provides an estimated value of the collapsible and expansive properties for soil is not available in Canada. For Phase I Assessments that we have prepared for TC Energy’s pipelines in the United States, we have referenced the U.S. Department of Agriculture’s National Resources Conservation Service (NRCS) database which provides estimates of soil expansive properties from low to moderate to high. For consistency with Phase I Assessments performed in the United States, we have classified soil units with no reports found of significant collapsible or expansive properties as low hazard areas. Soil collapse or expansion and associated structure damage could potentially occur in these areas; however, expansion of the soils is either not occurring, is too small in magnitude to have been widely reported or is located in too remote of an area to have been widely noticed. Moderate Hazard We classified moderate hazard collapsible or expansive soil areas along the pipeline alignment where soils with reported expansive properties are mapped, but there is no reported damage to structures or infrastructure.

Justification: We have classified areas with expansive soils with no reports found of structural damages (at the time of this assessment) as moderate potential expansive soil hazard areas, because while damage could potentially occur in these areas, expansion of the soils is either not occurring, is too small in magnitude to have been widely reported or is located in too remote of an area to have been widely noticed. High Hazard We classified high hazard collapsible or expansive soil areas along the alignment where expansive soils are mapped and where reports exist of structural damage associated with the expansive soil units.

Justification: Highly expansive soils have been found to cause structural damage to buildings and utilities; however, such occurrences are generally geographically isolated because they are also dependent on other factors such as climate, geology, and vegetation (Hamilton 1980). We have classified areas with mapped expansive soils and reports of structural damage as high potential expansive soil hazard areas. This is because such soils are known to cause structural damage; thus, the soils represent areas where a pipeline could potentially be affected. 4.0 RESULTS Overall, the potential for the geologic hazards that were addressed in this Phase I Assessment to affect the Project appears to be relatively low for most areas. However, we did identify two possible landslides, a low hazard liquefaction area and a low hazard collapsible and expansive soil area. In addition, the entire proposed pipeline appears to traverse a low hazard seismic ground shaking area and a low hazard fluid withdrawal subsidence area. In the following sections, we summarize the results for each hazard type by providing a brief discussion along with an overview map that illustrates the geographic distribution of the relevant hazard types. The Phase I Assessment results are also summarized in Table 2.

In the summary discussions that follow, the hazard classifications are relative to each hazard. For example, a high hazard with respect to subsidence does not necessarily mean that the pipeline is at a high potential for damage in high hazard areas, but rather that the hazard from subsidence is higher than in areas identified as low or moderate hazards.

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4.1 Landslide Hazards We identified and delineated two possible individual landslides within 30 m of the proposed pipeline alignment that may pose a hazard to the Project. An additional two possible individual landslides were identified within 100 m but are more than 30 m from the proposed alignment and therefore do not meet the classification criteria for low, moderate or high hazards. These may be of interest to NGTL should an alternate alignment be considered in future and are thus included herein. The identified landslide areas and steep slope areas generally coincide with a potentially unstable (Class IV) area identified in Golder’s terrain mapping (Golder 2020).

In addition, we identified 154 low hazard landslide areas within the project LiDAR data, identified solely on the basis of slope inclination. Slope inclinations were evaluated for a 200-m wide corridor centred on the proposed alignment. All identified landslide hazards are included in the hazard summary table presented in Table 2, and the general locations and distribution of landslide hazards are shown in Figure 2.

All four of the possible individual landslides were identified within the Raven River Valley (NGTLRR-LS-001 through NGTLRR-LS-004).  NGTLRR-LS-001 – Low Hazard - Shallow stream bank slump with lateral limits approximately 17 m north of the proposed alignment. Landslide movement is approximately parallel to the pipeline.  NGTLRR-LS-002 – Moderate Hazard -Dormant landslide crossing the proposed alignment with landslide movement approximately parallel to the proposed alignment. Internal landslide morphology appears rounded and subdued. Relief from head to toe area is approximately 10 m.  NGTLRR-LS-003: Originally mapped as part of NGTL landslide assessment (Golder 2016). Originally named NGTL-LS-629. Possibly older to dormant rotational landslide with movement obliquely away from the proposed pipeline. The headscarp of the feature is mapped approximately 38 m south of the proposed alignment. The nearby existing NGTL ROW does not appear to be disturbed (based on LiDAR review and 2015 helicopter reconnaissance). Confirmed as a low hazard landslide to existing NGTL pipeline during the 2015 helicopter reconnaissance; however, due to the distance from the proposed pipeline it does not meet the criteria for a low, moderate or high hazard landslide for this assessment.  NGTLRR-LS-004. Mapped as part of NGTL landslide assessment (Golder 2016). Originally named NGTL- LS-630. Possible landslide with movement parallel to the pipeline. Mapped approximately 54 m south of the proposed alignment. Existing NGTL ROW does not appear to be disturbed (based on LiDAR review and the 2015 helicopter reconnaissance). Confirmed as a low hazard landslide to the existing NGTL pipeline during the 2015 helicopter reconnaissance; however, due to the distance from the proposed pipeline it does not meet the criteria for a low, moderate or high hazard landslide for this assessment. 4.2 Seismic Hazards The Project is in an area of apparent low historical seismic activity (Halchuk et al. 2015b) and based on the references reviewed (Morozov et al. 2007; O’Rourke and Liu 1999, 2012; Wald et al. 1999), the Project appears to have a low potential for damage from future seismic activity. No active Quaternary-aged faults were identified near the pipeline alignment in any of the references reviewed for this project (Hamilton et al. 2012; Pana and Waters 2016; Prior et al. 2013). The Ancona Thrust fault is mapped to terminate approximately 22 km northwest of the alignment; as it does not appear to cross the proposed pipeline alignment, it is not considered a surface fault rupture hazard to the pipeline (Hamilton et. al 2012).

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Based on review of several earthquake databases containing records of earthquakes back to 1600 (Earthquakes Canada 2020, Natural Resources Canada 2018a; Halchuk et al. 2015a; Lamontagne et al. 2018; Stern et al. 2018), four earthquakes with magnitudes of 4.0 or greater have been recorded within 100 km of the proposed alignment and are listed below:  Magnitude 4.26 located approximately 24 km northwest of the alignment on August 9, 2014. (Stern et al. 2018)  Magnitude 4 located 25 km northwest of the alignment on September 3, 1984 (Halchuck et al. 2015).  Magnitude 4.1 located approximately 27 km northwest of the alignment on October 20, 1989 (Halchuck et al. 2015).  Magnitude 4 located approximately 61 km northwest of the alignment on March 10, 2019 (Earthquakes Canada 2020 and Stern et al. 2018).

It is not known how large the earthquakes in this area could be in the future and the potential hazard presented by this seismicity has not yet been fully assessed.

Projected 475-year return period PGA values for the pipeline alignment are low, averaging from between 0.03 and 0.04 g along the proposed pipeline (Halchuk et al. 2015b). The projected PGA values are within the low hazard classification for seismic shaking.

Approximately 2 percent of the Project is underlain by potentially liquefiable soil deposits (e.g., Holocene alluvial or lacustrine deposits), based on review of surficial geology, LiDAR data, and aerial imagery (Fenton et al. 2013; ESRI 2019; Google Earth 2019, Golder 2020); a length of approximately 375 m located in the Raven River valley between approximately KP 16+446 and KP 16+821). No “sensitive clays” like those of the Champlain Sea (e.g., the Leda Clay) were mapped in the vicinity of the Project. The projected PGA values for the liquefaction assessment are within the low hazard classification values of <0.1 g for the entire alignment; thus, the potential for seismically triggered liquefaction appears to be low.

The distribution of potential seismic hazards along the Project is depicted in Figure 3. A list of the references consulted to evaluate seismic hazards is provided in Sections 7.1 and 7.2. 4.3 Subsidence Hazards The proposed Project pipeline is entirely underlain by the Western Canada Sedimentary Basin (WCSB). The WCSB is one of the most prolific petroleum yielding basins in the world and is Canada’s dominant coal resource, making it a major target for coal, oil, oil sands, and gas exploration (Smith et al. 1994; Hay 1994). The WCSB has the potential for the presence of subsidence related to underground mines and fluid withdrawal in areas of oil and gas fields. Thus, these potential hazards may exist for the Project.

Potential subsidence hazards for the Project are considered low. Each type of potential subsidence hazard (e.g., karst, underground mines, and fluid withdrawal) is discussed separately below. 4.3.1 Karst We assessed karst subsidence hazards by reviewing previous mapping of bedrock geology, karst-prone areas, and karst features (e.g., sinkholes) compiled by government agencies. Based on the references and maps reviewed, the Project is not underlain by karst forming bedrock (Prior et al. 2013), and no karst features were mapped within 160 m of the alignment.

A list of the references consulted to evaluate karst subsidence hazards is provided in Sections 7.1 and 7.2.

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4.3.2 Underground Mines The Project is located outside the footprints of the major coal fields of the WCSB, does not cross coal agreement areas (e.g., leases), and no active or historic coal or metal mines were mapped within 160 m of the pipeline alignment (NRCan 2018; Alberta Energy 2020; AER 2008, 2015, 2016a, 2016b, 2020; Government of Alberta 2018). Thus, based on the references reviewed during this assessment, no underground mining subsidence hazards were identified along the proposed pipeline.

Sections 7.1 and 7.2 contain a list of the references consulted to evaluate underground mining subsidence hazards. 4.3.3 Fluid Withdrawal The Project crosses several areas of oil, gas and groundwater fluid withdrawal. Based on the references reviewed, no fluid withdrawal-related subsidence has been documented in the vicinity of the Project. A low hazard classification has been assigned to the Project because of the potential of over-exploitation of oil or gas, and possible subsequent ground subsidence.

The proposed pipeline alignment crosses the following areas with the potential for subsidence related to fluid withdrawal:  Oil and gas plays, including: Ostracod Airdrie, Banff Didsbury, Glauconitic Wetaskiwin, Olds, Rock Creek Sundre, Turner Valley Airdrie, Ellerslie , Fih Scales Brooks, Pekisko Airdrie, Second White Specs Airdrie, Viking , Wabamun Lesser Slave Lake, Winterburn-Nisku Rimbey, Shunda Airdrie, Swan Hills-Slave Point Whitecourt, Paskapoo-Edmonton Airdrie and Cardium (AER 2016c).  Viking and Cardium Oil Plays and Montney Hybrid Tight Gas/Shale Play (Alberta Oil & Gas Industry 2020).  Upper and Lower Mannville Oil and Gas Fields (Hayes et al. 2008).  Sunchild water aquifer (Andriashek and Lyster 2012). A summary of the identified fluid withdrawal subsidence hazards is presented in Table 2 and the distribution of potential subsidence hazards from fluid withdrawal is depicted in Figure 4. A list of the references consulted to evaluate fluid withdrawal subsidence hazards is provided in Sections 7.1 and 7.2. 4.4 Collapsible or Expansive Soils Based on the references reviewed for this assessment, the soils mapped along the Project are not reported to have significant collapsible or expansive properties (Agriculture and Agri-Food Canada 2015; Peters and Bowser 1957). The dominant surficial material underlying the proposed alignment is till. Glaciolacustrine sediments (clay) were identified in both the geohazard assessment and the terrain mapping between approximately KP 14+778 and KP 16+446 and between approximately KP 16+821 and KP 18+212 (Golder 2020). No significant collapsible or expansive properties were noted in any of the surficial materials. No instances of reported damage to structures or infrastructure were identified based on the data reviewed; thus, no moderate or high collapsible or expansive soil hazards were identified in this assessment. We have thus classified approximately 3 km of the proposed alignment (where it is underlain by glaciolacustrine sediments) as a low hazard collapsible or expansive soil area.

The distribution of potential collapsible or expansive soils for the Project is shown in Figure 5. A list of the references consulted to evaluate collapsible or expansive soil hazards is provided in Sections 7.1 and 7.2.

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5.0 RECOMMENDATIONS In this section, we recommend possible actions for each hazard type identified for the Project in this assessment. The recommendations are both general and tailored to the hazard type, hazard classification, and hazard location, as appropriate. In addition, the recommendations consider our qualitative understanding of the relative severity of the hazards. 5.1 All Hazards Many of the primary sources of data for this Phase I Assessment are publicly available, GIS-based geologic hazard mapping files. New geologic hazard maps, along with older maps that have been digitized, are frequently made available to the public as GIS-based files. We suggest that every 5 to 10 years, a data review be conducted to identify if there is any new information available that is pertinent to assessing geologic hazards for the Project. If new information is available, we recommend that the GIS layers and tables containing the results of this Phase I Assessment be updated accordingly.

At the time of this assessment, hazard classifications have been assigned based on the locations of the proposed pipeline alignment and do not take into consideration the design or construction methods for the pipeline. As the design progresses, the hazard classifications may require adjustment. For example, if a landslide is located between the entry and exit points at a trenchless crossing, and the depth of the landslide can be ascertained to be above the depth of the pipeline, a high or moderate hazard landslide may be reassigned a lower hazard classification. 5.2 Landslide Hazards We identified and delineated four possible individual landslides within 100 m of the proposed pipeline alignment and 154 steep slope low hazard landslide areas.

In general, we recommend that NGTL consider the following prior to, during, and after pipeline construction:  Further evaluate moderate and high hazard landslides in the field, initially through a ground reconnaissance, to better characterize each landslide (e.g., lateral extents, landslide depth, movement rate, activity, etc.).  During construction, minimize ground disturbance within and adjacent to all possible landslides, and follow best construction practices to avoid reactivating landslides.  During construction, follow best construction practices on and near all steep slopes.  Conduct a periodic visual inspection (such as during annual aerial reconnaissance) of landslide areas and steep slopes to evaluate if geomorphic indicators of landslide movement develop at these locations within or close to the pipeline. 5.3 Seismic Hazards The potential for seismic activity (e.g., strong shaking, liquefaction, surface fault rupture) to affect the Project appears to be low. In the event of a strong earthquake (magnitude 5 or greater) in the vicinity of the Project, we recommend that the ROW and proposed pipeline alignment be inspected for evidence of impacts or damage as outlined by Golder (2015b, 2016b).

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5.4 Subsidence Hazards Formation of subsidence hazards, by their nature, can be difficult to predict and identify, since most of the genesis and development of a subsidence feature occurs underground until the ground surface is breached. Underground openings or voids can be identified through the use of geophysics and drilling; however, the use of site-specific geophysics or drilling to identify voids may not be a realistic or cost-effective option.

While predicting the formation or expansion of subsidence hazards is difficult, there are usually some indicators of an imminent hazard. Indicators such as the formation of ground cracks, sudden changes in streams, or depressed ground, can all indicate that a sinkhole is propagating to the surface or that an existing sinkhole is expanding. Potential subsidence hazard areas could be visually inspected annually, such as during an aerial reconnaissance. 5.5 Collapsible or Expansive Soils There are no reports of soils with significant collapsible or expansive properties (according to the references reviewed), and there is no reported damage to structures or infrastructure. If during construction, soils are encountered that appear to have expansive or collapsible characteristics, we suggest that NGTL evaluate the sensitivity of their pipelines to soil volume changes. Depending on the results of this evaluation, we may recommend reassessing the hazard classification for collapsible and expansive soils.

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6.0 CLOSURE We appreciate the opportunity to produce this Phase I Assessment. The Phase I Assessment is intended to serve as a regional assessment of geologic hazards for the proposed Edson Mainline Loop No. 4 Raven River Section Project.

Our identification of geologic hazards and assignment of levels of relative severity are based on the information we reviewed for this assessment, as discussed in Section 3.0 and listed in the References section (Section 6). The potential hazard classifications derived for this Phase I Assessment are relative to the assessment and based on the criteria described herein.

The Phase I Assessment, being regional in scale, is intended to be used by NGTL and its representatives as a general database, for general awareness of geologic hazards along the Project, for regional planning purposes, and for identification of sites or areas for additional investigation. It is possible that geologic hazards may be present locally and may not have been identified in the Phase I Assessment, because of the scale of the assessment.

The Phase I Assessment should not be considered a site-specific investigation and should not be used for design purposes. The Phase I Assessment was performed based on regional-scale information and conditions present at the time of the assessment. These conditions may change due to changes to natural (e.g., geologic and climatic) processes and phenomena, or human activities.

Golder Associates Ltd.

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7.0 REFERENCES 7.1 Alphabetical References Agriculture and Agri-Food Canada. 1998. The Canadian System of Soil Classification, 3rd ed., Soil Classification Working Group, Agriculture and Agri-Food Canada Publication 1646, p.187.

Agriculture and Agri-Food Canada. 2015. Agriculture Regions of Alberta Soil Information Database Version 4.1. AGRISID 4.1 Digital map and database at 1:100,000. Online linkage: https://www.alberta.ca/agricultural- regions-of-alberta-soil-inventory-database.aspx

Alberta Energy Regulator (AER). 2008. Coalfields of the WCSB (GIS data, polygon features). Vector digital data, Alberta Geological Survey. DIG 2008_0349. Online linkage: http://ags.aer.ca/document/DIG/DIG_2008_0349.zip.

AER. 2015. Metallic Mineral Occurrence (GIS data, version 4). Vector digital data, Alberta Geological Survey. Online linkage: http://services2.arcgis.com/jQV6VMr2Loovu7GU/arcgis/rest/services/Metallic_Mineral_Occurrence_(v4_2 015_Jul_15)/FeatureServer.

AER. 2016a. Industrial Mineral Occurrence (GIS data, version 2). Vector digital data, Alberta Geological Survey. Online linkage: http://services2.arcgis.com/jQV6VMr2Loovu7GU/arcgis/rest/services/Industrial_Mineral_Occurrence_(v2_ 2016_Jun_17)/FeatureServer.

AER. 2016b. Industrial Mineral Mines (GIS data, version 1). Vector digital data, Alberta Geological Survey. Online linkage: http://services2.arcgis.com/jQV6VMr2Loovu7GU/arcgis/rest/services/Industrial_Mineral_Mines/FeatureSe rver.

AER. 2016c. Play Outlines (GIS data, version 4). Vector digital data, Alberta Geological Survey. Downloaded March 6, 2020 from: https://www.aer.ca/providing-information/data-and-reports/activity-and-data/play- workbook.

AER. 2020. Coal Mines in Alberta, digital data viewed on 06 March 2020 from https://extmapviewer.aer.ca/AERCoalMine/Index.html

Alberta Energy 2020. Coal Mineral Restriction, Agreements, and Coal Mines, digital data viewed from online Map Viewer on 6 March 2020 from https://gis.energy.gov.ab.ca/Geoview/Coal.

Alberta Oil & Gas Industry. 2020. Quarterly Update, Winter 2020, Alberta Oil & Gas Industry. Downloaded on 06 March 2020 from https://investalberta.ca/media/1080927/winter-oil-and-gas-quarterly-2020.pdf

Andriashek, L. D., and Lyster, S. 2012. Distribution of the Haynes and Sunchild Aquifers, Alberta, vector digital data: Alberta Geological Survey, Edmonton, Alberta. Online Linkage: https://ags.aer.ca/publications/DIG_2012_0027.html and https://ags.aer.ca/publications/DIG_2012_0028.html.

Aylsworth, J. M., Lawrence, D. E., and Guertin, J. 2000. Did two massive earthquakes in the Holocene induce widespread landsliding and near-surface deformation in part of the Ottawa Valley, Canada?: Geology, v. 28, no.10, p. 903-906.

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Bostock, H. S. 2014. Geological Survey of Canada. "A" Series Map 1254A, (ed. 2), 3 sheets, https://doi.org/10.4095/293408 (Open Access). Interactive Map online linkage: https://atlas.gc.ca/phys/en/

Boydell, A.N., Bayrock, L.A., Reimchen, T.H.F. 1974. Surficial Geology Rocky Mountain House (NTS 83B). AER/AGS Map 146. Online linkage: https://ags.aer.ca/publications/MAP_146.html

Coplin, L. S. and Galloway, D. 1999. Houston-Galveston, Texas; Managing coastal subsidence, in Galloway, D., Jones, D.R., and Ingebritsen, S.E., eds., 1999, Land subsidence in the United States: U.S. Geological Survey Circular 1182, p. 35-48.

Cruden, D. M. 1991. A simple definition of a landslide: Bulletin of the International Association of Engineering Geology, No. 43, p.27-29.

Cruden, D. M., and Varnes, D. J. 1996. Landslides Types and Processes. In Landslides: Investigation and Mitigation. Transportation Research Board, National Academy of Science, Special Report 247, Washington, D.C.

Earthquakes Canada, GSC, Earthquake Search (On-line Bulletin), http://earthquakescanada.nrcan.gc.ca/stndon/NEDB-BNDS/bulletin-en.php, Nat. Res. Can., Accessed on: March 6, 2020.

ESRI. 2020. World Imagery. Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community. Digital dataset accessed March 2020 online at http://www.arcgis.com/home/item.html?id=10df2279f9684e4a9f6a7f08febac2a9.

Fenton, M. M., Waters, E. l. J., Pawley, S. M., Atkinson, N., Utting, D. J., and Mckay, K. 2013. Surficial Geology of Alberta, Ungeneralized Digital Mosaic (GIS data, polygon features). Vector digital data, Alberta Geological Survey. DIG 2013_0001. Online linkage: https://ags.aer.ca/publications/DIG_2013_0001.html.

Ford, D. C. 1998. Principal features of evaporite karst in Canada, Fourth international conference on geomorphology, karst geomorphology, Italy 1997. Suppl. Geogr. Fis. Dinam. Quat. III, T.4 (1998), 11-19.

Galloway, D. and Riley, F. S. 1999. San Joaquin Valley, California; largest human alteration of the Earth’s surface, in Galloway, D., Jones, D. R., and Ingebritsen, S. E., eds., 1999, Land subsidence in the United States: U.S. Geological Survey Circular 1182, p. 23-34. Golder Associates Ltd. (Golder). 2015a. Phase I Geologic Hazards Assessment. NOVA Gas Transmission Limited System, Alberta and , Canada. Report submitted to TransCanada Feb. 2015.

Golder. 2015b. Framework for a TransCanada Earthquake Action (Response) Plan. Submitted to TransCanada 4 Jun. 2015 (Project Number 1525629.100). Golder. 2016a. Phase I Geologic Hazards Assessment – Landslide Hazards. NOVA Gas Transmission Limited System, Alberta and British Columbia, Canada. Report submitted to TransCanada 27 Jan. 2016.

Golder. 2016b. Revised Earthquake Action Plan Chart: email from D. West (Golder) to B. Liu (TransCanada), 7/11/2016.

Golder. 2017. Phase I Geologic Hazards Assessment – 2017 UPDATE. NOVA Gas Transmission Limited System Alberta, Canada. Report submitted to TransCanada Dec. 2017.

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Golder. 2018a. Phase I Geologic Hazards Assessment of Recently Built Segments of the NGTL Pipeline System, Alberta and British Columbia, Canada. NOVA Gas Transmission Limited System Alberta, Canada. Draft report submitted to TransCanada Nov. 2018.

Golder. 2018b. NGTL 2021 Expansion Program – Phase I Geologic Hazards Assessment. Final report submitted to NGTL December 2018.

Golder. 2020. Edson Mainline Loop No. 4 Raven River Section Project – Draft Preliminary Desktop Terrain Mapping and Geotechnical Soil Parameters for Stress Analyses Report submitted to TC Energy on March 23, 2020.

Google Earth. 2019. Google Earth 7.3.2.5776 (32-bit) Build Date March 5, 2019.

Government of Alberta. 2018. Minerals in Alberta: facts and stats. Open Government License. Online linkage: https://open.alberta.ca/dataset/ab9c2d60-03a6-4db1-9f81-5b233d5e41db/resource/153a0ff1-9276-44a7- 8639-74fbbbb02dd8/download/fsminerals.pdf

Halchuk, S., Allen, T. I., Rogers, G. C., and Adams, J. 2015a. Seismic Hazard Earthquake Epicentre File (SHEEF2010) used in the Fifth Generation Seismic Hazard Maps of Canada; Geological Survey of Canada, Open File 7724. doi:10.4095/296908.

Halchuk, S. C., Adams, J. E., and Allen, T. I. 2015b. Fifth Generation Seismic Hazard Model for Canada: Grid values of mean hazard to be used with the 2015 National Building Code of Canada; Geological Survey of Canada, Open File 7893. doi:10.4095/297378.

Hamilton, W. N., Langenberg, C. W., Price, M., and Chao, D. K. 2012. Major Bedrock Faults of Alberta, vector digital data, Alberta Geological Survey. DIG 2012-0016. Online linkage: http://www.ags.gov.ab.ca/publications/DIG/ZIP/DIG_2012_0016.zip.

Hamilton, J. J. 1980. Behavior of expansive soils in western Canada: National Research Council Canada, DBR Paper No. 1015, 19 p.

Hay, P. W. 1994. Oil and gas resources of the Western Canada Sedimentary Basin, in Geological Atlas of the Western Canada Sedimentary Basin, Calgary: Canadian Society of Petroleum Geologists, ch. 32.

Hayes, B. J. R., Christopher, J. E., Rosenthal, L., Los, G., McKercher, B., Minken, D. F., Trimblay, Y. M., and Fennell, J. W. 2008. Upper/Lower Mannville Oil and Gas Fields, vector digital data: Alberta Geological Survey. Online Linkage: https://ags.aer.ca/data-maps-models/digital-data.htm.

Klassen, R. W. 1989. Quaternary geology of the southern Canadian Interior Plains; in Chapter 2 of Quaternary Geology of Canada and Greenland, R.J. Fulton (ed.); Geological Survey of Canada, Geology of Canada, no 1. Online linkage: https://geoscan.nrcan.gc.ca/starweb/geoscan/servlet.starweb

Lamontagne, M. Halchuk, S., Cassidy, J. F., and Rogers, G. C. 2018. Significant Canadian earthquakes 1600-2017; Geological Survey of Canada, Open File 8285. doi: 10.4095/311183. Online linkage: https://geoscan.nrcan.gc.ca/starweb/geoscan/servlet.starweb?path=geoscan/fulle.web&search1=R=3111 83.

Lopez, G.P., Budney, H.E., Weiss, J.A. and Pawlowicz, J.G. 2020. Minerals of Alberta; Alberta Energy Regulator / Alberta Geological Survey, AER/AGS Map 590, scale 1:1 250 000. Online linkage: https://ags.aer.ca/publications/MAP_590.html

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Morozov. I., Chubak, G. and Litwin, L. 2007. Rebuilding a Regional Seismograph Network in Southern Saskatchewan: in Summary of Investigations 2007, Volume 1, Saskatchewan Geological Survey, Sask. Industry Resources, Misc. Report 2007-4.1, Paper A-1, 7 p.

Natural Resources Canada (NRCan). 2009. Atlas of Canada 6th Edition (archival version) Physiographic Regions; Natural Resources Canada website. Online linkage: http://atlas.nrcan.gc.ca/site/english/maps/ geology.html.

NRCan. 2018a. Earthquakes Canada, GSC, Earthquake Search (Online Bulletin), accessed 2 Oct. 2018 from http://earthquakescanada.nrcan.gc.ca/stndon/NEDB-BNDS/bull-eng.php.

NRCan. 2018b. Principal mineral areas, producing mines and oil and gas fields in Canada, sixty-eighth edition. Geological Survey of Canada. Map 900A, scale 1:6 000 000 available at: http://ftp.geogratis.gc.ca/pub/nrcan_rncan/Mining-industry_Industrie-miniere/

O’Rourke, M. J. and Liu, X. 1999. Response of buried pipelines subject to earthquake effects: Multidisciplinary Center for Earthquake Engineering Research Monograph Series MCEER-99-MN03.

O’Rourke, M. J. and Liu, X. 2012. Seismic Design of Buried and Offshore Pipelines. Multidisciplinary Center for Earthquake Engineering Research. Monograph Series MCEER-12-MN04.

Pana, D. I. and Waters, E. J. 2016. GIS compilation of structural elements in Alberta, version 3.0 (GIS data, line features). DIG 2003-0012. Online linkage: https://ags.aer.ca/publications/DIG_2003_0012.html#summary

Pavelko, M. T., Wood, D. B. and Laczniak, R. J. 1999. Las Vegas, Nevada; Gambling with water in the desert, in Galloway, D., Jones, D. R., and Ingebritsen, S. E., eds., 1999, Land subsidence in the United States: U.S. Geological Survey Circular 1182, p. 49-64.

Peters, T.W. and Bowser, W.E. 1957. Soil Survey of Rocky Mountain House Sheet. University of Alberta Bulletin No. 22-1, Alberta Soil Survey Report No. 19. Online Linkage: https://open.alberta.ca/publications/ss-19

Poland, J. F. 1984. Guidebook to studies of land subsidence due ground-water withdrawal: Prepared for the International Hydrological Programme, Working Group 8.4, United Nations Educational, Scientific, and Cultural Organization (UNESCO), 340 p.

Prior, G. J., Hathway, B., Glombick, P. M., Pana, D. I., Banks, C. J., Hay, D. C., Schneider, C. L., Grobe, M., Elgr, R., Weiss, J. A. 2013. Bedrock Geology of Alberta & Structures (GIS data, line features). Vector digital data, Alberta Geological Survey. DIG 2013-18, DIG 2013-0019, DIG 2013-0020 and DIG 2013-0021. Online linkage: https://ags.aer.ca/data-maps-models/digital-data.htm.

Quinn, P., Hutchinson, D. J., Diederichs, M. S., Rowe, R. K., Harrap, R., and Alvarez, J. 2007a. A Digital Inventory of Landslides in Champlain Clay: 60th Canadian Geotechnical Conference, Ottawa, October, p. 713-720.

Quinn, P., Diederichs, M. S., Hutchinson, D. J., and Rowe, R. K. 2007b. An Exploration of the Mechanics of Retrogressive Landslides in Sensitive Clay: 60th Canadian Geotechnical Conference, Ottawa, October, p. 721-727.

Rokosh, C. D., Lyster, S., Anderson, S. D. A., Beaton, A. P., Berhane, H., Brazzoni, T., Chen, D., Cheng, Y., Mack, T., Pana, C. and Pawlowicz, J.G. 2012. Summary of Alberta's shale- and siltstone-hosted hydrocarbon resource potential; Energy Resources Conservation Board, ERCB/AGS Open File Report 2012-06, 327 p.

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Rokosh, C. D., Lyster, S., Anderson, S. D. A., Beaton, A.P., Berhane, H., Brazzoni, T., Chen, D., Cheng, Y., Mack, T., Pana, C. and Pawlowicz, J.G. 2013. Alberta Shale Report: Outlines of Evaluated Shale and Siltstone Units (GIS data, polygon features). Vector digital data, Energy Resources Conservation Board/ Alberta Geological Survey DIG 2013-0024. Online linkage: http://www.ags.gov.ab.ca/publications/DIG/ZIP/DIG_2013_0024.zip

Shetson, I. 1987. Quaternary geology, ; Alberta research Council, ARC/AGS Map 207. Online linkage: https://ags.aer.ca/publications/MAP_207.html#summary

Shetson, I. 1990. Quaternary geology, ; Alberta Research Council, ARC/AGS Map 213. Online linkage: https://ags.aer.ca/publications/MAP_213.html

Smith, G. G., Cameron, A. R., and Bustin, R. M. 1994. Coal Resources of the Western Canada Sedimentary Basin, in Geological Atlas of the Western Canada Sedimentary Basin, Calgary: Canadian Society of Petroleum Geologists, ch. 33.

Stern, V. H., Schultz, R. J., Shen, L., Gu, Y. J., and Eaton, D. W. 2018. Alberta earthquake catalogue, version 6.0 (GIS data, point features); Alberta Energy Regulator, AER/AGS Digital Dataset 2013-0017.

Wald, D. J., V. Quitoriano, T. H. Heaton, and Kanamori, H. 1999. Relationship between Peak Ground Acceleration, Peak Ground Velocity, and Modified Mercalli Intensity in California: Earthquake Spectra, v. 15, no. 3, p. 557-564.

Whyatt, J. and Varley, F. 2008. Catastrophic Failures of Underground Evaporite Mines, Proceedings of the 27th International Conference on Ground Control in Mining, July 29 – July 31, 2008, Morgantown, West Virginia. West Virginia University, 2008. NIOSH – Spokane Research Laboratory, Spokane, WA.

Youd, T. L., Idriss, I. M., Andrus, R. D., Arango, I., Castro, G., Christian, J. T., Dobry, R., Finn, W. D., Harder Jr., L. F., Hynes, M. E., Ishihara, K., Koester, J. P., Liao, S. S. C., Marcuson III, W. F., Martin, G. R., Mitchell, J. K., Moriwaki, Y., Power, M. S., Robertson, P. K., Seed, R. B., and Stokoe II, K. H. 2001. Liquefaction resistance of soils summary report from the 1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils. Journal o Geotechnical and Geoenvironmental Engineering, v. 127, no. 10, p. 817-833.

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7.2 References by Hazard Type Landslide Cruden (1991)

Cruden and Varnes (1996)

ESRI (2020)

Golder (2015a, 2016a, 2017, 2018)

Google EarthTM (2019) Seismic: Earthquake Shaking Golder (2015b, 2016b)

Halchuk et al. (2015a; 2015b)

Lamontagne et al. (2018)

Morozov et al. (2007)

NRCan (2018a)

O’Rourke and Liu (1999, 2012)

Stern et al. (2018)

Wald et al. (1999) Seismic: Soil Liquefaction Aylsworth et al. 2000)

Fenton et al. (2013)

ESRI (2020)

Google Earth (2019)

Halchuk et al. (2015b)

O’Rourke and Liu (1999, 2012)

Quinn et al. (2007a, b)

Youd et al. (2001) Seismic: Surface Fault Rupture Hamilton et al. (2012)

Pana and Waters (2016)

Prior et al. (2013)

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Subsidence: Karst Ford (1998)

Prior et al. (2013) Subsidence: Underground Mine Alberta Energy (2020)

AER (2008, 2015, 2016a, 2016b, 2019)

Whyatt and Varley (2008)

Government of Alberta (2018)

NRCan (2018b)

Smith et al. (1994) Subsidence: Fluid Withdrawal AER (2016c)

Alberta Oil & Gas Industry (2020)

Andriashek and Lyster (2012)

Coplin and Galloway (1999)

Galloway and Riley (1999)

Hay (1994)

Hayes et al. (2008)

Rokosh et al. (2012, 2013)

Smith et al. (1994)

Pavelko et al. (1999)

Poland (1984) Collapsible and Expansive Soils Agriculture and Agri-Food Canada (1998, 2015)

Hamilton (1980)

Peters and Bowser (1957)

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TABLES

Table 1 - Edson Mainline Loop No. 4 Raven River Section Project - Phase I Geologic Hazards Classification Summary

Table 2 - Edson Mainline Loop No. 4 Raven River Section - Phase I Summary of Hazards

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Table 1: Edson Mainline Loop No. 4 Raven River Section Project - Phase I Geologic Hazards Classification Summary Hazard Classification Hazard Type Comments Low Moderate High . Slopes greater than 14 percent (8 degrees) with no mapped We have assumed that the constructed ROW will be landslides. approximately 30 m centered on the pipeline centerline. Thus, we . Shallow, small stream bank slump between 15 m and 30 m of . Apparently dormant landslide that crosses or is within 15 m of the consider landslides located within 15 m of the proposed pipeline the pipeline alignment. pipeline alignment. alignment to pose a higher hazard/threat both during and post- . Relict landslide that crosses or is within 30 m of the pipeline . Apparently or possibly active landslide located between 15 m and . Apparently or possibly active landslide that crosses or is construction of the pipeline. alignment with low potential for renewed activity. 30 m of the pipeline alignment. within 15 m of the pipeline alignment. . Apparently dormant landslide between 15 and 30 m of the . Debris flow run-out (depositional) area that crosses the pipeline . Debris flow source area or debris flow channel that crosses Landslide activity levels are defined as follows: Landslide pipeline alignment. alignment. the pipeline alignment. . Active Landslide: A landslide with the most recent . Historical landslide that has been remediated and shows no . Rock fall deposition zone within 30 m of the pipeline alignment but . Rock fall deposition area that crosses the pipeline movement apparently occurring within the last 100 years. signs of movement post-remediation, that crosses or is within that does not cross the pipeline alignment, with an active source alignment. . Dormant Landslide: A landslide with the most recent 30 m of the pipeline alignment. area and with potential for future rock deposition across the pipeline movement apparently occurring more than 100 years ago. . Rock fall deposition zone within 30 m of the alignment but alignment. . Relict Landslide: A landslide that occurred under different that does not cross the pipeline alignment, with a depleted climatic or geomorphic conditions and is unlikely to rock fall source area and the source slope has stabilized. reactivate under current. Assuming probabilistic seismic hazard ground shaking risk level Seismic (Earthquake < 0.15 g peak ground acceleration (PGA) 0.15 g to 0.25 g PGA > 0.25 g PGA of 10% probability of exceedance in a 50-year period (475-year Shaking) return period). Unconsolidated Holocene sediment primarily consisting of silt to gravel Unconsolidated Holocene sediment primarily consisting of silt to meeting the following criteria: gravel meeting one of the following criteria: . 0.1 g to 0.2 g PGA. . < 0.1 g PGA Unconsolidated Holocene sediment primarily consisting of silt . Groundwater less than 9 metres deep. . Zone of alluvium (river or stream) is at least 90 m wide where to gravel meeting both of the following criteria: Assuming probabilistic seismic hazard ground shaking risk level Seismic (Liquefaction . Zone of alluvium (river or stream) is at least 90 m wide where crossed by the pipeline. . > 0.2 g PGA. of 10% probability of exceedance in a 50-year period (475-year [buoyancy, settlement and crossed by the pipeline. Or . Groundwater less than about 3 metres deep. return period) combined with interpretations of nature, age, and lateral spreading]) Or . 0.1 g to 0.2 g PGA . Zone of alluvium (river or stream) is at least 90 m wide saturation of soil. . > 0.2 g PGA. . Groundwater is deeper than about 9 m where crossed by the pipeline. . Groundwater between 3 and 9 metres deep. . Zone of alluvium (river or stream) is at least 90 m wide where . Zone of alluvium (river or stream) is at least 90 m wide where crossed by the pipeline. crossed by the pipeline. . Faults reported as active within the Quaternary, but with no . Geomorphic lineaments observed on aerial photographs, or during information as to age of most recent movement or slip-rate. aerial reconnaissance, that displace Holocene or Late Pleistocene . Faults reported as having experienced movement within . Faults active in the Quaternary with the most recent deposits. the last 15,000 years (i.e., Holocene or historic movement). Seismic movement 130,000 years ago or older, and slip-rate of less . Faults with most recent movement between 130,000 and 750,000 . Faults reported as having a slip-rate greater than

(Fault Rupture) than 0.2 mm/year. years ago, and slip-rate of 0.2 to 1 mm/year. 5 mm/year . Faults active in the Quaternary with most recent movement . Faults active in the Quaternary with most recent movement 750,000 . Faults with most recent movement between 15,000 and 750,000 years ago or older, and slip-rate of less than years ago or older, and slip-rate between 1 to 5 mm/year. 750,000 years ago, and slip-rate of 1 to 5 mm/year. 1 mm/year. . Growth faults with evidence of historical displacement. . Sinkholes or areas with evidence of subsurface voids . Mapped sinkholes or evidence of subsurface voids . Areas where carbonate or evaporite bedrock is exposed at (e.g., disappearing streams) between 60 and 160 metres from the (e.g., disappearing streams) within 60 metres of the the surface or where it directly underlies unconsolidated Subsidence (Karst) pipeline alignment. pipeline alignment. surface deposits but where specific identification or mapping . Areas mapped as karst by federal or provincial agencies, but with no . Areas along the pipeline alignment historically impacted by of karst features did not exist. mapped sinkholes or evidence of sinkholes in aerial photographs. sinkholes or other karst phenomena. . Areas where the pipeline alignment is within 60 m of . Within region or area of underground mines, but pipeline evidence of an underground mine, a mapped underground . Areas where the pipeline alignment is within 60 to 160 m of a Subsidence (Underground alignment is between 160 m and 300 m from mapped mine or underground mine-related feature (such as an mapped underground mine or underground mine-related feature Mine) underground mine, and there is no evidence of surface airshaft or mine entrance). (such as an airshaft or mine entrance). subsidence. . Areas along the pipeline historically impacted by subsidence resulting from underground mines. . Pipeline alignment crosses areas that contain oil and gas or groundwater well fields that have reported or documented evidence of damaging fluid withdrawal subsidence, such as . Pipeline alignment crosses areas that contain well fields for subsidence that has damaged roads and structures . Pipeline alignment crosses areas that contain oil and gas or Subsidence (Fluid oil and gas explorations, or areas with major groundwater (e.g., roads frequently repaired from subsidence, badly groundwater well fields with reports of fluid withdrawal subsidence, Withdrawal) aquifers, but with no reports of fluid withdrawal-related damaged buildings, damaged utilities). but with no reports of damage resulting from this subsidence. subsidence. . Pipeline alignment crosses areas that have documented evidence of fluid withdrawal subsidence that has resulted in significant differential displacement, such as the formation of fissures or faults. . Areas along the alignment where mapped soils are not . Areas along the alignment where soils with reported expansive . Areas along the alignment where expansive soils are Collapsible/Expansive reported to have significant collapsible or expansive properties are mapped, but there is no reported damage to structures mapped, and where reports exist of structural damage Soils properties, and there is no reported damage to structures or or infrastructure. associated with the expansive soil units. infrastructure.

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Table 2: Proposed Edson Mainline Loop No. 4 Raven River Section - Phase I Summary of Hazards Landslide Hazards Hazard Hazard ID Comments Source START_KP END_KP On_CL Classification Shallow streambank slump with lateral limits approximately 17 m north of the proposed alignment. NGTLRR-LS-001 Low 2015 LiDAR imagery Landslide movement is approximately parallel to the pipeline. 16434 16477 N Dormant landslide crossing the proposed alignment with landslide movement approximately parallel to the NGTLRR-LS-002 Moderate proposed alignment. Internal landslide morphology appears rounded and subdued. Relief from head to toe2015 LiDAR imagery area is approximately 10 m. 16427 16456 Y Originally named NGTL-LS-629. Possibly older to dormant rotational landslide with movement obliquely away from the proposed pipeline. Headscarp mapped approx 38m south of the proposed alignment. NGTLRR-LS-003 N/A Golder 2016, Updated as appropriate for proposed pipeline, based on 2015 LiDAR Nearby existing NGTL ROW does not appear to be disturbed. Does not meet the criteria for a low, moderate or high hazard landslide for this assessment due to distance from alignment. 16354 16440 N Originally named NGTL-LS-630. Possible landslide with movement parallel to the pipeline. Mapped NGTLRR-LS-004 N/A approximately 54 m south of the proposed alignment. Does not meet the criteria for a low, moderate or Golder 2016, Updated as appropriate for proposed pipeline, based on 2015 LiDAR high hazard landslide for this assessment based on distance to proposed alignment. 16345 16397 N

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Table 2: Proposed Edson Mainline Loop No. 4 Raven River Section - Phase I Summary of Hazards Landslide Hazards - Steep Slope Areas Hazard START_K Hazard ID Comments Source END_KP On_CL Classification P NGTLRR-LS-1001 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 64 72 Y NGTLRR-LS-1002 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 36 95 N NGTLRR-LS-1003 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 157 217 N NGTLRR-LS-1004 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 99 247 N NGTLRR-LS-1005 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 451 485 N NGTLRR-LS-1006 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 396 444 N NGTLRR-LS-1007 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 270 777 Y NGTLRR-LS-1008 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 548 588 N NGTLRR-LS-1009 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 371 559 N NGTLRR-LS-1010 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 703 786 N NGTLRR-LS-1011 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 786 801 Y NGTLRR-LS-1012 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 762 817 N NGTLRR-LS-1013 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 840 865 Y NGTLRR-LS-1014 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 909 925 Y NGTLRR-LS-1015 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 943 972 Y NGTLRR-LS-1016 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 1038 1217 Y NGTLRR-LS-1017 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 1200 1282 N NGTLRR-LS-1018 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 1265 1305 Y NGTLRR-LS-1019 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 1335 1367 N NGTLRR-LS-1020 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 1397 1520 Y NGTLRR-LS-1021 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 1681 1776 N NGTLRR-LS-1022 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 1593 2042 Y NGTLRR-LS-1023 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 1803 1873 N NGTLRR-LS-1024 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 2063 2090 N NGTLRR-LS-1025 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 2081 2125 N NGTLRR-LS-1026 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 2052 2429 N NGTLRR-LS-1027 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 2138 2156 Y NGTLRR-LS-1028 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 2158 2200 N NGTLRR-LS-1029 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 2216 2481 Y NGTLRR-LS-1030 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 2511 2686 Y NGTLRR-LS-1031 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 2497 2580 N NGTLRR-LS-1032 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 2867 2945 Y NGTLRR-LS-1033 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 2770 2822 N NGTLRR-LS-1034 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 2840 3004 N NGTLRR-LS-1035 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 3084 3166 N NGTLRR-LS-1036 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 3146 3212 N NGTLRR-LS-1037 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 3212 3261 N

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Table 2: Proposed Edson Mainline Loop No. 4 Raven River Section - Phase I Summary of Hazards Landslide Hazards - Steep Slope Areas Hazard START_K Hazard ID Comments Source END_KP On_CL Classification P NGTLRR-LS-1038 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 3389 3467 N NGTLRR-LS-1039 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 3436 3567 Y NGTLRR-LS-1040 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 3575 3588 Y NGTLRR-LS-1041 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 3655 3658 Y NGTLRR-LS-1042 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 3662 4336 Y NGTLRR-LS-1043 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 3777 3822 N NGTLRR-LS-1044 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 3867 3944 N NGTLRR-LS-1045 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 4156 4208 N NGTLRR-LS-1046 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 4425 4494 Y NGTLRR-LS-1047 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 4567 4592 Y NGTLRR-LS-1048 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 4568 4595 N NGTLRR-LS-1049 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 4621 4759 Y NGTLRR-LS-1050 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 4696 4785 N NGTLRR-LS-1051 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 4773 4817 N NGTLRR-LS-1052 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 4777 4835 N NGTLRR-LS-1053 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 4766 4839 N NGTLRR-LS-1054 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 4879 5031 Y NGTLRR-LS-1055 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 4884 4915 N NGTLRR-LS-1056 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 5108 5135 Y NGTLRR-LS-1057 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 5231 5339 N NGTLRR-LS-1058 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 5247 5274 Y NGTLRR-LS-1059 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 5255 5342 N NGTLRR-LS-1060 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 5370 5382 Y NGTLRR-LS-1061 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 5351 5414 N NGTLRR-LS-1062 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 5414 5605 N NGTLRR-LS-1063 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 5505 5552 N NGTLRR-LS-1064 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 5565 5580 Y NGTLRR-LS-1065 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 5600 5672 Y NGTLRR-LS-1066 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 5701 5767 N NGTLRR-LS-1067 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 5752 5796 N NGTLRR-LS-1068 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 5824 5834 Y NGTLRR-LS-1069 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 5868 5951 N NGTLRR-LS-1070 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 5896 5911 Y NGTLRR-LS-1071 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 5955 6005 N NGTLRR-LS-1072 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 6017 6108 N NGTLRR-LS-1073 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 6014 6057 Y NGTLRR-LS-1074 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 6129 6168 N

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May 2020 Project No. 20138120

Table 2: Proposed Edson Mainline Loop No. 4 Raven River Section - Phase I Summary of Hazards Landslide Hazards - Steep Slope Areas Hazard START_K Hazard ID Comments Source END_KP On_CL Classification P NGTLRR-LS-1075 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 6036 6114 N NGTLRR-LS-1076 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 6181 6194 Y NGTLRR-LS-1077 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 6194 6236 N NGTLRR-LS-1078 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 6409 6444 N NGTLRR-LS-1079 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 6383 6415 Y NGTLRR-LS-1080 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 6391 6444 N NGTLRR-LS-1081 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 6975 6976 Y NGTLRR-LS-1082 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 7023 7043 Y NGTLRR-LS-1083 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 7063 7090 N NGTLRR-LS-1084 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 7135 7177 N NGTLRR-LS-1085 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 7213 7249 Y NGTLRR-LS-1086 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 7388 7443 N NGTLRR-LS-1087 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 7429 7451 Y NGTLRR-LS-1088 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 7445 7486 N NGTLRR-LS-1089 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 7460 7480 Y NGTLRR-LS-1090 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 7492 7542 N NGTLRR-LS-1091 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 7517 7588 N NGTLRR-LS-1092 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 7522 7538 Y NGTLRR-LS-1093 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 7668 7702 Y NGTLRR-LS-1094 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 7867 7914 Y NGTLRR-LS-1095 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 7898 8073 N NGTLRR-LS-1096 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 7977 8123 Y NGTLRR-LS-1097 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 8057 8117 N NGTLRR-LS-1098 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 8031 8072 N NGTLRR-LS-1099 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 8232 8312 N NGTLRR-LS-1100 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 8381 8409 Y NGTLRR-LS-1101 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 8353 8421 N NGTLRR-LS-1102 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 8432 8528 N NGTLRR-LS-1103 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 8434 8483 N NGTLRR-LS-1104 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 8548 8589 Y NGTLRR-LS-1105 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 8633 8727 N NGTLRR-LS-1106 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 8884 8916 N NGTLRR-LS-1107 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 8970 9103 Y NGTLRR-LS-1108 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 9025 9101 N NGTLRR-LS-1109 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 9127 9146 Y NGTLRR-LS-1110 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 9210 9229 Y NGTLRR-LS-1111 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 9233 9919 Y

Page 3 of 5 June 2020 Page 33 of 132 NOVA Gas Transmission Ltd. Attachment 6 NGTL West Path Delivery 2022 Desktop Geohazards Preliminary Assessment

May 2020 Project No. 20138120

Table 2: Proposed Edson Mainline Loop No. 4 Raven River Section - Phase I Summary of Hazards Landslide Hazards - Steep Slope Areas Hazard START_K Hazard ID Comments Source END_KP On_CL Classification P NGTLRR-LS-1112 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 9936 10076 Y NGTLRR-LS-1113 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 9966 10059 N NGTLRR-LS-1114 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 10099 11128 Y NGTLRR-LS-1115 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 10140 10185 N NGTLRR-LS-1116 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 10185 10282 N NGTLRR-LS-1117 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 10310 10828 N NGTLRR-LS-1118 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 11169 11193 N NGTLRR-LS-1119 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 11228 11305 N NGTLRR-LS-1120 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 11367 11420 Y NGTLRR-LS-1121 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 11406 11446 N NGTLRR-LS-1122 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 11346 11483 N NGTLRR-LS-1123 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 11583 11643 Y NGTLRR-LS-1124 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 11633 11703 N NGTLRR-LS-1125 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 11740 11779 Y NGTLRR-LS-1126 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 11654 11803 N NGTLRR-LS-1127 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 11725 11839 N NGTLRR-LS-1128 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 11737 11841 N NGTLRR-LS-1129 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 11875 11934 N NGTLRR-LS-1130 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 11817 11938 N NGTLRR-LS-1131 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 11926 12070 Y NGTLRR-LS-1132 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 12106 12175 N NGTLRR-LS-1133 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 12148 12228 N NGTLRR-LS-1134 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 12280 12347 N NGTLRR-LS-1135 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 12519 12559 N NGTLRR-LS-1136 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 12374 12422 N NGTLRR-LS-1137 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 12517 12539 Y NGTLRR-LS-1138 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 12606 12645 N NGTLRR-LS-1139 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 12625 12648 Y NGTLRR-LS-1140 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 12715 12731 Y NGTLRR-LS-1141 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 12518 12713 N NGTLRR-LS-1142 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 12761 12781 N NGTLRR-LS-1143 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 12830 12891 N NGTLRR-LS-1144 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 12911 12958 N NGTLRR-LS-1145 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 15530 15641 N NGTLRR-LS-1146 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 15735 15777 N NGTLRR-LS-1147 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 16062 16223 Y NGTLRR-LS-1148 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 16274 16283 Y

Page 4 of 5 June 2020 Page 34 of 132 NOVA Gas Transmission Ltd. Attachment 6 NGTL West Path Delivery 2022 Desktop Geohazards Preliminary Assessment

May 2020 Project No. 20138120

Table 2: Proposed Edson Mainline Loop No. 4 Raven River Section - Phase I Summary of Hazards Landslide Hazards - Steep Slope Areas Hazard START_K Hazard ID Comments Source END_KP On_CL Classification P NGTLRR-LS-1149 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 16290 16427 Y NGTLRR-LS-1150 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 16825 16878 Y NGTLRR-LS-1151 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 17262 17324 Y NGTLRR-LS-1152 Low Slope >= 14% LiDAR obtained from Midwest Surveys February 2020. LiDAR collection dates 2013 and 2015. 17987 18131 N

Page 5 of 5 June 2020 Page 35 of 132 NOVA Gas Transmission Ltd. Attachment 6 NGTL West Path Delivery 2022 Desktop Geohazards Preliminary Assessment

May 2020 Project No. 20138120

Table 2: Proposed Edson Mainline Loop No. 4 Raven River Section - Phase I Summary of Hazards Seismic Hazards - Ground Shaking Hazard ID Hazard Classification Comments Source START_KP END_KP On_CL PGA <0.15 g based on 10% probability of exceedance in a 50-year period (475-year return NGTLRR-SM-001 Low Halchuck et al. 2015b period) 0 18212 Y

Page 1 of 1 June 2020 Page 36 of 132 NOVA Gas Transmission Ltd. Attachment 6 NGTL West Path Delivery 2022 Desktop Geohazards Preliminary Assessment

May 2020 Project No. 20138120 Table 2: Proposed Edson Mainline Loop No. 4 Raven River Section - Phase I Summary of Hazards Seismic Hazards - Liquefaction Hazard ID Hazard Classification Comments Source START_KP END_KP On_CL Area of interpreted Holocene alluvial deposits LiDAR imagery; ESRI imagery, Boydell et al. 1974 (surficial geology; NGTLRR-LI-001 Low identified by Golder with PGAs less than 0.1 g. Golder 2020 (terrain mapping). 16446 16821 Y

Page 1 of 1 June 2020 Page 37 of 132 NOVA Gas Transmission Ltd. Attachment 6 NGTL West Path Delivery 2022 Desktop Geohazards Preliminary Assessment

May 2020 Project No. 20138120

Table 2: Proposed Edson Mainline Loop No. 4 Raven River Section - Phase I Summary of Hazards Ground Subsidence - Fluid Withdrawal Hazard ID Hazard Classification Comments Source START_KP END_KP On_CL Paskapoo-Edmonton Airdrie Gas Play, Fish Scales Brooks Gas Play, Cardium Pigeon Lake Oil and Gas Play, Swan Hills-Slave Point Whitecourt Oil and Gas Play, Shunda Airdrie Oil and Gas Play, Winterburn-Nisku Rimbey Oil and Gas AER 2016c, Alberta Oil & Gas Industry 2019, Hayes et al. NGTLRR-FW-001 Low Play, Wabamun Lesser Slave Lake Oil and Gas Play, Viking Gull Lake Oil and 2008 Gas Play, Second White Specks Airdrie Oil and Gas Play, Pekisko Airdrie Oil and Gas Play, Ellerslie Lesser Slave Lake Oil and Gas Play, Turner Valley Airdrie Oil and Gas Play and Rock Creek Sundre Oil 0 795 Y Paskapoo-Edmonton Airdrie Gas Play, Fish Scales Brooks Gas Play, Cardium Pigeon Lake Oil and Gas Play, Swan Hills-Slave Point Whitecourt Oil and Gas Play, Shunda Airdrie Oil and Gas Play, Winterburn-Nisku Rimbey Oil and Gas AER 2016c, Alberta Oil & Gas Industry 2019, Andriashek NGTLRR-FW-002 Low Play, Wabamun Lesser Slave Lake Oil and Gas Play, Viking Gull Lake Oil and and Lyster 2012, Hayes et al. 2008 Gas Play, Second White Specks Airdrie Oil and Gas Play, Pekisko Airdrie Oil and Gas Play, Ellerslie Lesser Slave Lake Oil and Gas Play, Turner Valley Airdrie Oil and Gas Play and Rock Creek Sundre Oi 795 3336 Y Paskapoo-Edmonton Airdrie Gas Play, Fish Scales Brooks Gas Play, Cardium Pigeon Lake Oil and Gas Play, Swan Hills-Slave Point Whitecourt Oil and Gas Play, Shunda Airdrie Oil and Gas Play, Winterburn-Nisku Rimbey Oil and Gas AER 2016c, Alberta Oil & Gas Industry 2019, Andriashek NGTLRR-FW-003 Low Play, Wabamun Lesser Slave Lake Oil and Gas Play, Viking Gull Lake Oil and and Lyster 2012, Hayes et al. 2008 Gas Play, Second White Specks Airdrie Oil and Gas Play, Pekisko Airdrie Oil and Gas Play, Ellerslie Lesser Slave Lake Oil and Gas Play, Turner Valley Airdrie Oil and Gas Play and Rock Creek Sundre Oi 3336 3449 Y Paskapoo-Edmonton Airdrie Gas Play, Fish Scales Brooks Gas Play, Cardium Pigeon Lake Oil and Gas Play, Swan Hills-Slave Point Whitecourt Oil and Gas Play, Shunda Airdrie Oil and Gas Play, Winterburn-Nisku Rimbey Oil and Gas AER 2016c, Alberta Oil & Gas Industry 2019, Andriashek NGTLRR-FW-004 Low Play, Wabamun Lesser Slave Lake Oil and Gas Play, Viking Gull Lake Oil and and Lyster 2012, Hayes et al. 2008 Gas Play, Second White Specks Airdrie Oil and Gas Play, Pekisko Airdrie Oil and Gas Play, Ellerslie Lesser Slave Lake Oil and Gas Play, Turner Valley Airdrie Oil and Gas Play and Rock Creek Sundre Oi 3449 3889 Y Paskapoo-Edmonton Airdrie Gas Play, Fish Scales Brooks Gas Play, Cardium Pigeon Lake Oil and Gas Play, Swan Hills-Slave Point Whitecourt Oil and Gas Play, Shunda Airdrie Oil and Gas Play, Winterburn-Nisku Rimbey Oil and Gas AER 2016c, Alberta Oil & Gas Industry 2019, Andriashek NGTLRR-FW-005 Low Play, Wabamun Lesser Slave Lake Oil and Gas Play, Viking Gull Lake Oil and and Lyster 2012, Hayes et al. 2008 Gas Play, Second White Specks Airdrie Oil and Gas Play, Pekisko Airdrie Oil and Gas Play, Ellerslie Lesser Slave Lake Oil and Gas Play, Turner Valley Airdrie Oil and Gas Play and Rock Creek Sundre Oi 3167 3358 Y Paskapoo-Edmonton Airdrie Gas Play, Fish Scales Brooks Gas Play, Cardium Pigeon Lake Oil and Gas Play, Swan Hills-Slave Point Whitecourt Oil and Gas Play, Shunda Airdrie Oil and Gas Play, Winterburn-Nisku Rimbey Oil and Gas AER 2016c, Alberta Oil & Gas Industry 2019, Andriashek NGTLRR-FW-006 Low Play, Wabamun Lesser Slave Lake Oil and Gas Play, Viking Gull Lake Oil and and Lyster 2012, Hayes et al. 2008 Gas Play, Second White Specks Airdrie Oil and Gas Play, Pekisko Airdrie Oil and Gas Play, Ellerslie Lesser Slave Lake Oil and Gas Play, Turner Valley Airdrie Oil and Gas Play and Rock Creek Sundre Oi 3889 7718 Y Paskapoo-Edmonton Airdrie Gas Play, Fish Scales Brooks Gas Play, Cardium Pigeon Lake Oil and Gas Play, Swan Hills-Slave Point Whitecourt Oil and Gas Play, Shunda Airdrie Oil and Gas Play, Winterburn-Nisku Rimbey Oil and Gas AER 2016c, Alberta Oil & Gas Industry 2019, Hayes et al. NGTLRR-FW-007 Low Play, Wabamun Lesser Slave Lake Oil and Gas Play, Viking Gull Lake Oil and 2008 Gas Play, Second White Specks Airdrie Oil and Gas Play, Pekisko Airdrie Oil and Gas Play, Ellerslie Lesser Slave Lake Oil and Gas Play, Turner Valley Airdrie Oil and Gas Play and Rock Creek Sundre Oi 7718 8047 Y Paskapoo-Edmonton Airdrie Gas Play, Fish Scales Brooks Gas Play, Cardium Pigeon Lake Oil and Gas Play, Swan Hills-Slave Point Whitecourt Oil and Gas Play, Shunda Airdrie Oil and Gas Play, Winterburn-Nisku Rimbey Oil and Gas AER 2016c, Alberta Oil & Gas Industry 2019, Andriashek NGTLRR-FW-008 Low Play, Wabamun Lesser Slave Lake Oil and Gas Play, Viking Gull Lake Oil and and Lyster 2012, Hayes et al. 2008 Gas Play, Second White Specks Airdrie Oil and Gas Play, Pekisko Airdrie Oil and Gas Play, Ellerslie Lesser Slave Lake Oil and Gas Play, Turner Valley Airdrie Oil and Gas Play and Rock Creek Sundre Oi 8047 14255 Y Paskapoo-Edmonton Airdrie Gas Play, Fish Scales Brooks Gas Play, Cardium Pigeon Lake Oil and Gas Play, Swan Hills-Slave Point Whitecourt Oil and Gas Play, Shunda Airdrie Oil and Gas Play, Winterburn-Nisku Rimbey Oil and Gas AER 2016c, Alberta Oil & Gas Industry 2019, Andriashek NGTLRR-FW-009 Low Play, Wabamun Lesser Slave Lake Oil and Gas Play, Viking Gull Lake Oil and and Lyster 2012, Hayes et al. 2008 Gas Play, Second White Specks Airdrie Oil and Gas Play, Pekisko Airdrie Oil and Gas Play, Ellerslie Lesser Slave Lake Oil and Gas Play, Turner Valley Airdrie Oil and Gas Play and Rock Creek Sundre Oi 14255 15288 Y Paskapoo-Edmonton Airdrie Gas Play, Fish Scales Brooks Gas Play, Cardium Pigeon Lake Oil and Gas Play, Swan Hills-Slave Point Whitecourt Oil and Gas Play, Shunda Airdrie Oil and Gas Play, Winterburn-Nisku Rimbey Oil and Gas AER 2016c, Alberta Oil & Gas Industry 2019, Andriashek NGTLRR-FW-010 Low Play, Wabamun Lesser Slave Lake Oil and Gas Play, Viking Gull Lake Oil and and Lyster 2012 Gas Play, Second White Specks Airdrie Oil and Gas Play, Pekisko Airdrie Oil and Gas Play, Ellerslie Lesser Slave Lake Oil and Gas Play, Turner Valley Airdrie Oil and Gas Play and Rock Creek Sundre Oi 15288 16475 Y Paskapoo-Edmonton Airdrie Gas Play, Fish Scales Brooks Gas Play, Cardium Pigeon Lake Oil and Gas Play, Swan Hills-Slave Point Whitecourt Oil and Gas Play, Shunda Airdrie Oil and Gas Play, Winterburn-Nisku Rimbey Oil and Gas NGTLRR-FW-011 Low Play, Wabamun Lesser Slave Lake Oil and Gas Play, Viking Gull Lake Oil and AER 2016c, Alberta Oil & Gas Industry 2019 Gas Play, Second White Specks Airdrie Oil and Gas Play, Pekisko Airdrie Oil and Gas Play, Ellerslie Lesser Slave Lake Oil and Gas Play, Turner Valley Airdrie Oil and Gas Play and Rock Creek Sundre Oi 16475 18212 Y

Page 1 of 1 June 2020 Page 38 of 132 NOVA Gas Transmission Ltd. Attachment 6 NGTL West Path Delivery 2022 Desktop Geohazards Preliminary Assessment

May 2020 Project No. 20138120 Table 2: Proposed Edson Mainline Loop No. 4 Raven River Section - Phase I Summary of Hazards Collapsible/Expansive Soils Hazard ID Hazard Classification Comments Source START_KP END_KP On_CL No significant collapsible or expansive properties. No reported damage from Agriculture and Agri-Food Canada 2015; Peters and Bowser 1957; NGTLRR-CES-001 Low collapsible and expansive soils. Golder 2020 14778 16446 Y No significant collapsible or expansive properties. No reported damage from Agriculture and Agri-Food Canada 2015; Peters and Bowser 1957; NGTLRR-CES-002 Low collapsible and expansive soils. Golder 2020 16821 18212 Y

Page 1 of 1 June 2020 Page 39 of 132 NOVA Gas Transmission Ltd. Attachment 6 NGTL West Path Delivery 2022 Desktop Geohazards Preliminary Assessment

FIGURES Figure 1 - Edson Mainline Loop No. 4 Raven River Section - Overview Map Figure 2 - Edson Mainline Loop No. 4 Raven River Section - Landslide Hazard Areas Figure 3 - Edson Mainline Loop No. 4 Raven River Section - Seismic Hazard Areas (Ground Shaking and Liquefaction) Figure 4 - Edson Mainline Loop No. 4 Raven River Section - Fluid Withdrawal Subsidence Hazard Areas Figure 5 - Edson Mainline Loop No. 4 Raven River Section - Expansive and Collapsible Soils Hazard Areas

June 2020 Page 40 of 132 NOVA Gas Transmission Ltd. Attachment 6 NGTL West Path Delivery 2022 645000 650000 655000 Desktop Geohazards Preliminary Assessment KEY MAP LEGEND (! KILOMETRE POST British Columbia Alberta STUDY ROUTE*

Fort St. John ! ! ! Fort McMurray Dawson Creek !Grande Prairie

Prince George !

5770000 Edmonton 5770000 ! Williams Lake 18+000 ! 18+212 (! ^_ Project Calgary (! Location ! Vancouver ! SCALE 1:40,000,000 17+000

(! 16+000

(! r ive R en av 15+000 R B ea ver (! C reek 14+000

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(! NOTE(S) *STUDY ROUTE OBTAINED FROM NGTL 2020-02-12. **ALTERNATE STUDY ROUTE OBTAINED FROM NGTL 2019-12-06.

5+000 REFERENCE(S) AB HYDROGRAPHIC LABELS DATA OBTAINED FROM ALTALIS LTD. © GOVERNMENT OF ALBERTA (! 2015. ALL RIGHTS RESERVED. TOPOGRAPHIC MAP © ESRI AND ITS LICENSORS. USED UNDER nyCree k to 4+000 LICENSE, ALL RIGHTS RESERVED. r S

5760000 e 5760000 PROJECTION: UTM ZONE 11 DATUM: NAD 83 Upp (!

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APPROVED MN PROJECT NO. CONTROL REV. FIGURE

645000 650000 655000 20138120 3000 0 PATH: I:\CLIENTS\TC_ENERGY\20138120\Mapping\Products\Soil&Terrain\20138120_Edson_Mainline_Loop_4_Raven_River_Fig1_OverviewMap_Rev0.mxdPATH: PRINTED ON: 2020-05-2212:51:16 AT: PM

June 2020 Page 41 of 1132 0 NOVA Gas Transmission Ltd. Attachment 6 NGTL West Path Delivery 2022 645000 650000 655000 Desktop Geohazards Preliminary Assessment KEY MAP LEGEND (! KILOMETRE POST British Columbia Alberta STUDY ROUTE*

Fort St. John ! ! 60 METRE CORRIDOR ! Fort McMurray Dawson Creek ! Grande Prairie LANDSLIDE HAZARD Prince George !

5770000 Edmonton 5770000 LANDSLIDE MODERATE HAZARD AREA ! Williams Lake 18+000 ! 18+212 (! ^_ LANDSLIDE LOW HAZARD AREA Project Calgary (! Location ! LANDSLIDE HAZARD AREA AWAY FROM ALIGNMENT Vancouver ! STEEP SLOPE LOW HAZARD AREA 17+000 SCALE 1:40,000,000

(! 16+000

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(!

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Burnstick 7+000 Lake 0 2,000 4,000 (!

6+000 1:60,000 METRES

(! NOTE(S) *STUDY ROUTE OBTAINED FROM NGTL 2020-02-12. NGTLRR-LS-001 **ALTERNATE STUDY ROUTE OBTAINED FROM NGTL 2019-12-06. REFERENCE(S) AB HYDROGRAPHIC LABELS DATA OBTAINED FROM ALTALIS LTD. © GOVERNMENT OF ALBERTA 5+000 (! y Cree 4+000 2015. ALL RIGHTS RESERVED. HILLSHADE OBTAINED FROM TC ENERGY. on k t 16+500 TOPOGRAPHIC MAP © ESRI AND ITS LICENSORS. USED UNDER LICENSE, ALL RIGHTS r S 5760000 e 5760000 RESERVED. Up p (! (! PROJECTION: UTM ZONE 11 DATUM: NAD 83 CLIENT 3+000 NOVA GAS TRANSMISSION LTD.

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PREPARED CO NGTLRR-LS-004 REVIEWED AD APPROVED MN

SCALE 1:6,000 PROJECT NO. CONTROL REV. FIGURE

645000 650000 655000 20138120 3000 0 PATH: I:\CLIENTS\TC_ENERGY\20138120\Mapping\Products\Soil&Terrain\20138120_Edson_Mainline_Loop_4_Raven_River_Fig2_LandslideHazardAreas_Rev0.mxdPATH: PRINTED ON: 2020-05-2212:41:57 AT: PM

June 2020 Page 42 of 2132 0 NOVA Gas Transmission Ltd. Attachment 6 NGTL West Path Delivery 2022 645000 650000 655000 Desktop Geohazards Preliminary Assessment KEY MAP LEGEND (! KILOMETRE POST British Columbia Alberta STUDY ROUTE*

Fort St. John ! ! SIESMIC (LIQUEFACTION) HAZARD ! Fort McMurray Dawson Creek !Grande Prairie LOW

Prince George !

5770000 Edmonton 5770000 PEAK GROUND ACCELERATION ! Williams Lake 18+000 ! 10% IN 50 YEARS EXCEEDANCE 18+212 (! ^_ Project Calgary 0.01G - 0.05G (! Location ! Vancouver ! SCALE 1:40,000,000 17+000

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REFERENCE(S) 5+000 AB HYDROGRAPHIC LABELS DATA OBTAINED FROM ALTALIS LTD. © GOVERNMENT OF ALBERTA 2015. ALL RIGHTS RESERVED. TOPOGRAPHIC MAP © ESRI AND ITS LICENSORS. USED UNDER (! LICENSE, ALL RIGHTS RESERVED. nyCree to k 4+000 PROJECTION: UTM ZONE 11 DATUM: NAD 83 r S 5760000 Uppe 5760000 (! CLIENT NOVA GAS TRANSMISSION LTD. 3+000

(! PROJECT 2+000 EDSON MAINLINE LOOP No. 4 RAVEN RIVER SECTION (! 1+000 TITLE (! EDSON MAINLINE LOOP No. 4 - RAVEN RIVER 0+000 SECTION SEISMIC HAZARD AREAS (GROUND

SHAKING AND LIQUEFACTION) IF THISMEASUREMENT DOES NOTMATCH WHATIS SHOWN, THE SHEET SIZEHAS BEEN MODIFIED FROM:ANSI B (!

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June 2020 Page 43 of 3132 0 NOVA Gas Transmission Ltd. Attachment 6 NGTL West Path Delivery 2022 645000 650000 655000 Desktop Geohazards Preliminary Assessment KEY MAP LEGEND (! KILOMETRE POST British Columbia Alberta STUDY ROUTE*

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June 2020 Page 44 of 4132 0 NOVA Gas Transmission Ltd. Attachment 6 NGTL West Path Delivery 2022 645000 650000 655000 Desktop Geohazards Preliminary Assessment KEY MAP LEGEND (! KILOMETRE POST British Columbia Alberta STUDY ROUTE*

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Electronic Files

June 2020 Page 46 of 132 NOVA Gas Transmission Ltd. Attachment 6 NGTL West Path Delivery 2022 Desktop Geohazards Preliminary Assessment

golder.com

June 2020 Page 47 of 132 NOVA Gas Transmission Ltd. NGTL West Path Delivery 2022 Attachment 6

Desktop Geohazards Preliminary Assessment

ABC Section NOVA Gas Transmission Ltd. Attachment 6 NGTL West Path Delivery 2022 Desktop Geohazards Preliminary Assessment

NOVA GAS TRANSMISSION LTD.

WESTERN ALBERTA SYSTEM MAINLINE LOOP NO. 2 ALBERTA BRITISH COLUMBIA SECTION (ABC SECTION)

DESKTOP GEOHAZARDS PRELIMINARY ASSESSMENT

REV 1

NGTL BGC PROJECT NO.: 0098187 01251 PROJECT NO.: DOCUMENT NO.: 01251-BGC-C-RP-0001_01 DATE: May 27, 2020

June 2020 Page 48 of 132 NOVA Gas Transmission Ltd. Attachment 6 NGTL West Path Delivery 2022 Desktop Geohazards Preliminary Assessment

Suite 500 - 1000 Centre Street NE Calgary, AB Canada T2E 7W6 Telephone (403) 250-5185 Fax (403) 250-5330

May 27, 2020 Project No.: 0098187

Joni Lei G. Cardona, P.Eng. Project Manager Canada Gas Projects - Pipeline TC Energy Corporation 450 – 1 Street SW Calgary, AB T2P 5H1

Dear Joni Lei, Re: Western Alberta System Mainline Loop No. 2 Alberta British Columbia Section (ABC Section), Desktop Geohazards Preliminary Assessment – Rev 1

Please find attached revision 1 of our above-referenced report dated May 27, 2020. Should you have any further questions or comments, please do not hesitate to contact us at the number listed above.

Yours sincerely,

BGC ENGINEERING INC. per:

Luc Toussaint, PG.Dip., P.Eng. Senior Geotechnical Engineer

June 2020 Page 49 of 132 NOVA Gas Transmission Ltd. Attachment 6 NGTL West Path Delivery 2022 Desktop Geohazards Preliminary Assessment

EXECUTIVE SUMMARY

BGC Engineering Inc. (BGC) has been retained by NOVA Gas Transmission Ltd. (NGTL), a wholly owned subsidiary of TransCanada PipeLines Limited (TCPL), an affiliate of TC Energy Corporation (TC Energy), to conduct a desktop geohazard assessment for the Western Alberta System Mainline Loop No. 2 Alberta British Columbia Section (ABC Section) as part of the NGTL West Path Delivery 2022 Project. The desktop geohazard assessment consisted in identifying credible geohazard threats to the buried pipeline and above-ground infrastructure and assigning to each credible threat a hazard rating. The hazard rating indicates the level to which each credible hazard is expected to impact the design and construction of the pipeline, in terms of the expected need for additional, more detailed assessment work and overall effort in mitigation. Where required, those more detailed assessments and design of mitigation are planned as part of subsequent stages of the pipeline design process. Geohazards included in this study are classified into the following types: • Landslide (including rockfall, rockslide, rock avalanche, debris slide, earth landslide, debris flow, debris flood, snow and ice avalanche, and outburst flood) • Hydrotechnical (including channel scour and channel degradation) • Seismic (including ground shaking, liquefaction and fault rupture) • Subsidence (including karst, compressible soils, mining and fluid withdrawal) • Geotechnical (including problematic soils, permafrost degradation, and peat/organic soils) • Geochemical (including acid rock drainage and metal leaching). This document presents the methodology employed in developing the hazard inventories associated with each of the hazard types. The rating of the hazards aligned with the following framework: • Low Hazard: Standard construction practice and typical designs are likely adequate to manage the hazard, with a relatively low level of effort. We found 19 discrete low hazard pipeline segments between all hazard types. • Moderate Hazard: Field review and generic mitigation designs are likely required to manage the hazard, with an intermediate level of effort. We found 19 discrete moderate hazard pipeline segments between all hazard types. • High Hazard: Detailed field review and site-specific mitigation are likely required to manage the hazard, with a relatively high level of effort. Two high seismic hazard pipeline segments were identified; these will require careful further study but may not warrant major additional effort in construction to protect pipeline integrity. The results of the assessment are described and qualified in the text herein and presented in tabulated and drawing form.

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TABLE OF CONTENTS

EXECUTIVE SUMMARY ...... i TABLE OF CONTENTS ...... ii LIMITATIONS ...... vi 1.0 INTRODUCTION ...... 1 1.1. Western Alberta System Mainline Loop No. 2 Alberta British Columbia Section (ABC) ...... 1 1.2. Terms of Reference ...... 1 2.0 SCOPE OF WORK ...... 2 2.1. Authorship ...... 3 3.0 BACKGROUND ...... 4 3.1. Jurisdiction ...... 4 3.2. Physiographic and Topographic Setting ...... 4 3.3. Climate and Hydrology ...... 4 3.4. Geological Setting ...... 6 3.5. Historic Geohazard Events ...... 7 3.6. Background Data ...... 8 4.0 METHODOLOGY BY GEOHAZARD TYPE ...... 9 4.1. Terrain Mapping ...... 9 4.2. Landslide Hazards ...... 9 4.2.1. Hazard Rating ...... 10 4.3. Hydrotechnical Hazards ...... 11 4.3.1. Hydrotechnical Hazard Description ...... 11 4.3.2. Hydrotechnical Hazard Mapping Objective ...... 12 4.3.3. Hydrotechnical Hazard Mapping Methodology ...... 12 4.4. Seismic Hazards ...... 13 4.4.1. Seismic Shaking ...... 13 4.4.2. Liquefaction ...... 14 4.4.3. Earthquake-Triggered Landslides ...... 15 4.4.4. Surface Faulting ...... 17 4.5. Subsidence Hazards ...... 18 4.5.1. Hazard rating ...... 18 4.6. Geotechnical Hazards ...... 19 4.6.1. Hazard rating ...... 19 4.7. Geochemical Hazards ...... 20 4.7.1. Geologic Unit Permissive Likelihood ...... 20 4.7.2. Mineral Occurrences ...... 21 4.7.3. Desktop Geochemical Hazard Rating ...... 21 5.0 RESULTS AND RECOMMENDATIONS ...... 23 5.1. Landslide Hazards ...... 23 5.2. Potential Hydrotechnical Hazard Sites...... 24

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5.3. Seismic Hazards ...... 24 5.4. Subsidence Hazards ...... 27 5.5. Geotechnical Hazards ...... 27 5.6. Geochemical Hazards ...... 28 5.7. Uncertainties ...... 31 5.7.1. Landslide Hazard Assessment ...... 31 5.7.2. Hydrotechnical Hazard Assessment ...... 31 5.7.3. Seismic Hazard Assessment ...... 31 5.7.4. Subsidence Hazard Assessment ...... 32 5.7.5. Geotechnical Hazard Assessment ...... 32 5.7.6. Geochemical Hazard Assessment ...... 33 6.0 FUTURE WORK ...... 34 6.1. Landslide Hazards ...... 34 6.2. Hydrotechnical Hazards ...... 34 6.3. Seismic Hazards ...... 34 6.4. Subsidence Hazards ...... 35 6.5. Geotechnical Hazards ...... 35 6.6. Geochemical Hazards ...... 35 7.0 CLOSURE ...... 36 REFERENCES ...... 37

LIST OF TABLES

Table 3-1. Regulated Dams Upstream of the Project (Alberta Dam Safety Map, April 30, 2020)...... 6 Table 4-1. Landslide hazard types included in this study...... 9 Table 4-2. General application of the hazard ratings for landslide hazards...... 11 Table 4-3. Hydrotechnical hazard classification typical indicators...... 13 Table 4-4. Combination rules for rock and soil site classes where rock is between 1 and 3 m below ground surface...... 14 Table 4-5. Relative liquefaction hazard derived from liquefaction susceptibility and

PGAsite...... 14 Table 4-6. Geologic groups by surficial material...... 15 Table 4-7. Map units, lithologic descriptions, and interpreted geologic groups along the ABC Section. Geology from Stockmal and Fallas (2015)...... 16 Table 4-8. Subsidence hazard types included in this study...... 18 Table 4-9. General application of the hazard ratings for subsidence geohazards...... 18 Table 4-10. Geotechnical hazard types included in this study...... 19

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Table 4-11. General application of the hazard ratings for geotechnical hazards...... 19 Table 5-1. Potential landslide hazard inventory...... 23 Table 5-2. Potential hydrotechnical hazard inventory...... 24 Table 5-3. Potential subsidence hazard inventory...... 27 Table 5-4. Geotechnical hazard inventory...... 28 Table 5-5. Desktop Geochemical Hazard Assessment for the ABC Section, Alberta...... 29

LIST OF FIGURES

Figure 3-1. Climate normal data (1981 to 2010) for Beaver Mines Environment and Climate Change Canada climate station...... 5 Figure 3-2. Maximum 1-day Total Precipitation (Climatedata.ca, April 30, 2020)...... 6 Figure 4-1. Critical acceleration versus slope angle for three geologic groups and two groundwater conditions. From Wilson and Keefer (1985)...... 16 Figure 4-2. Geochemical hazard rating criteria...... 22 Figure 5-1. Reference-condition (site class C) PGA hazard curve...... 26 Figure 5-2. Reference-condition (site class C) uniform hazard response spectra for 1:100, 1:475, 1:1000, and 1:2,475 annual exceedance probabilities. Reference-condition (site class C) uniform hazard response spectra for 1:100, 1:475, 1:1,000, and 1:2,475 annual exceedance probabilities...... 26

LIST OF DRAWINGS

DRAWING 01 Loop Section Overview Map DRAWING 02 Surficial Geology DRAWING 03 Bedrock Geology DRAWING 04A Terrain Mapping DRAWING 04B Terrain Map Legend DRAWING 05 Hydrotechnical Hazards Map DRAWING 06 Landslide Hazards Map DRAWING 07 Seismic Hazards Map DRAWING 08 Subsidence Hazards Map DRAWING 09 Geotechnical Hazards Map DRAWING 10 Geochemical Hazards Map

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LIST OF APPENDICES

APPENDIX A DESCRIPTIVE LIST OF ALL GEOHAZARD CLASSES AND TYPES APPENDIX B RATIONALE FOR CLASSIFICATION FOR LANDSLIDE, SUBSIDENCE, GEOTECHNICAL, AND SEISMIC HAZARDS RATING APPENDIX C LANDSLIDE HAZARDS INVENTORY APPENDIX D HYDROTECHNICAL HAZARDS INVENTORY APPENDIX E SEISMIC HAZARDS INVENTORY APPENDIX F SUBSIDENCE HAZARDS INVENTORY APPENDIX G GEOTECHNICAL HAZARDS INVENTORY APPENDIX H GEOCHEMICAL HAZARDS INVENTORY

June 2020 Page 54 of 132 NOVA Gas Transmission Ltd. Attachment 6 NGTL West Path Delivery 2022 Desktop Geohazards Preliminary Assessment

LIMITATIONS

BGC Engineering Inc. (BGC) prepared this document for the account of NOVA Gas Transmission Ltd. The material in it reflects the judgment of BGC staff in light of the information available to BGC at the time of document preparation. Any use which a third party makes of this document or any reliance on decisions to be based on it is the responsibility of such third parties. BGC accepts no responsibility for damages, if any, suffered by any third party as a result of decisions made or actions based on this document.

As a mutual protection to our client, the public, and ourselves all documents and drawings are submitted for the confidential information of our client for a specific project. Authorization for any use and/or publication of this document or any data, statements, conclusions or abstracts from or regarding our documents and drawings, through any form of print or electronic media, including without limitation, posting or reproduction of same on any website, is reserved pending BGC’s written approval. A record copy of this document is on file at BGC. That copy takes precedence over any other copy or reproduction of this document.

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1.0 INTRODUCTION NOVA Gas Transmission Ltd.’s (NGTL) West Path Delivery 2022 Project involves looping a section of the existing Western Alberta Mainline System with new 48-inch diameter gas pipeline. BGC understands that the project team has set a preliminary route, and is currently in the stages of permitting, field investigations planning and conceptual design for implementation in 2020 and beyond.

1.1. Western Alberta System Mainline Loop No. 2 Alberta British Columbia Section (ABC) The Western Alberta System Mainline Loop No. 2 Alberta British Columbia Section (referenced as ABC Section or the Section in this report) is 5,211 m long, located entirely in Alberta, between Sentinel and Phillipps Lake near . An existing NGTL facility (ABC Border Meter Station) is at the east end of the ABC Section at kilometre post (KP) 0+000. Most of the ABC Section follows the existing NGTL pipelines, offset to south by several tens of metres, except between KP 2+800 and 3+400 where the ABC Section deviates to the south by up to 200 m. The considered ABC Section alignment is illustrated in Drawing 01. The work discussed in this report focuses on the ABC Section and was based on a proposed route alignment (080424-2020-SH-08-0001 Rev 2) received from NGTL on April 9, 2020.

1.2. Terms of Reference This work was carried out under the Master Service Agreement (MSA) No. 4600007427, Amending Agreement No. 01 currently in place between NGTL and BGC, and under PO# 4500309880.

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2.0 SCOPE OF WORK This desktop assessment has the objective of identifying credible geohazard threats to the buried pipeline and above-ground infrastructure and assigning to each credible threat a hazard rating. The hazard rating indicates the level to which each credible hazard is expected to impact the design and construction of the pipeline, in terms of additional, more detailed assessment work and overall effort in mitigation. Where required, those more detailed assessments and design of mitigation are planned as part of subsequent stages of the pipeline design process. For the purpose of this work, the term ‘geohazard’ includes geological conditions and processes that could threaten the integrity of the pipeline. Geohazards included in this study are classified as: • Landslide (including rockfall, rockslide, rock avalanche, debris slide, earth landslide, debris flow, debris flood, snow and ice avalanche, and outburst flood) • Hydrotechnical (including channel scour and channel degradation) • Seismic (including ground shaking, liquefaction and fault rupture) • Subsidence (including karst, compressible soils, mining and fluid withdrawal) • Geotechnical (including problematic soils, permafrost degradation, and peat/organic soils) • Geochemical (including acid rock drainage and metal leaching). Appendix A provides a detailed description of each geohazard type. This is not a comprehensive list of all possible geohazards globally; rather, it represents a set of geohazards and geohazard scenarios which, at a screening level, we expect could be present along the ABC Section. Geohazards associated with volcanic activity, as an example, are not included as there are no known volcanic sources regionally. Volcanic geohazards are therefore considered non-credible, in general, to the ABC Section. The geohazards listed in Appendix A are all expected to have some credible potential to occur somewhere along the Section. The purpose of this report is to document the preliminary desktop-level geohazard assessment for the ABC Section. It will generate an inventory of credible hazards along the pipeline, each rated qualitatively on potential impacts to the proposed pipeline. It provides a basis for further, more detailed studies and, where required, mitigation design. BGC has developed a three-level hazard rating system which has been applied to each of the geohazard types: • Low Hazard: Standard construction practice and typical designs are likely adequate to manage the hazard, with a relatively low level of effort. • Moderate Hazard: Field review and generic mitigation designs are likely required to manage the hazard, with an intermediate level of effort. • High Hazard: Detailed field review and site-specific mitigation are likely required to manage the hazard, with a relatively high level of effort. The specific criteria for assigning the hazard rating to a site or pipeline segment are different for each geohazard type and are detailed further in Section 4.0.

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This is not a risk assessment, nor was it informed by any specific field investigation or data collection. BGC relied on spatial and other data provided by NGTL, and on publicly available resources such as geological reports and maps.

2.1. Authorship This work was a collaborative effort conducted by several qualified subject matter experts, each of whom takes professional responsibility for their specific geohazards and sections of this report. Responsible authors and relevant sections are listed below. • Dave Gauthier, Ph.D., P.Geo. (BC), P.Eng. (BC): Landslide, subsidence, and geotechnical geohazards • Rebecca Lee, P.Eng. (BC, AB), P.Geo. (BC): Hydrotechnical geohazards • Martin Zaleski, M.Sc., P.Geo. (BC, AB): Seismic geohazards • Sharon Blackmore, Ph.D., P.Geo. (BC): Geochemical geohazards. In addition, technical review was conducted by: • Pete Quinn, Ph.D., ing., P.Eng. (AB, BC): Overall content, with focus on landslide, subsidence, and geotechnical geohazards • Pascal Szeftel, Ph.D., ing., P.Eng. (BC, AB): Hydrotechnical geohazards • Bevin Harrison, M.A.Sc., P.Geo. (BC): Geochemical geohazards.

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3.0 BACKGROUND

3.1. Jurisdiction The NGTL West Path Delivery 2022 project is located in Alberta. BGC understands that the NGTL West Path Delivery 2022 project is under the authority of the Canada Energy Regulator (CER) and is expected to meet the Onshore Pipeline Regulation (OPR) and CSA Z662 standard.

3.2. Physiographic and Topographic Setting The ABC Section lies within the High Rock Range of the Rocky Mountains Natural Region of southern Alberta. From KP 0 to 4.0 it is within the Montane subregion and from KP 4.0 to KP 5.2 it is within the Subalpine subregion (Natural Regions Committee, 2006). The pipeline ascends from 1,370 m elevation at the eastern end of the route in the Crowsnest Valley to 1,620 m at Phillipps Pass. North of Phillipps Pass, Tecumseh Peak rises to 2,548 m. South of Phillipps Pass, Crowsnest Ridge reaches 1,903 m. The ABC Section straddles the continental divide. The wide, main valley is dotted with large lakes including Crowsnest and Island Lakes in Alberta, and in BC. The flows east and is part of the headwaters of the . Summit Lake drains westward to Summit Creek and is part of the headwaters.

3.3. Climate and Hydrology

The climate in the Crowsnest Valley reflects the interaction between regional-scale weather systems, topography/elevation, distance from the Pacific Ocean, prevailing winds, and season. Although large-scale airflows moving in from the coast bring moist, marine air from west to east, the study area is located in a rain shadow. Low pressure systems force cold, arctic air into the valley, and high winds are common (DeMarchi, 2011). Figure 3-1 presents climate normals for the Beaver Mines climate station1, located in the 34 km southwest of the Section, for the years 1981 to 2010. Precipitation exhibits low variability in monthly totals throughout the year, except for May and June which are the wettest months. Average lowest monthly temperature occurs in December/January (-5°C) and highest in July/August (23°C).

1 Latitude 49.47 N, Longitude 114.18 W, Elevation 1,257 m. Station meets the United Nations’ World Meteorological Organization (WMO) standards.

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Figure 3-1. Climate normal data (1981 to 2010) for Beaver Mines Environment and Climate Change Canada climate station.

Climatedata.ca (April 30, 2020) estimates that average annual precipitation for the 1981 to 2010 period was 654 mm. Under a high-emissions-scenario climate change projection (RCP 8.5)2, this is predicted to increase by 11% for the 2051-2080 period. For 1981 to 2010, Climatedata.ca estimates an average annual temperature of 2.7°C, which is projected to increase to 6.4°C for the 2051-2080 period under a high emissions scenario3. Average values mask the high variability in daily and monthly climate that is typical for the area. Figure 3-2 shows the range in observed maximum 1-day precipitation events, and projected future increases. Hydrology within the Crowsnest region is dominated by the spring freshet; however, additional peaks in flow can occur throughout the summer due to large convective storm events, as well as rain-on-snow flood events in the spring and autumn. Alberta Dam Safety (April 30, 2020) reports that two Low Consequence Dams are located upstream of the proposed pipeline (Table 3-1). DataBC (April 30, 2020) does not identify any regulated dams upstream of the project area.

2 As defined by Climatedata.ca (2020), “This scenario assumes that greenhouse gas concentrations will continue to increase at approximately the same rate as they are increasing today. Under this scenario, the planet’s radiative forcing will have increased by 8.5 W/m2 by the year 2100, relative to 1750 (and continues to rise well after 2100). In the scientific literature, this scenario is referred to as “RCP8.5.” Of the four greenhouse gas pathways (RCP8.5, RCP6.0, RCP4.5, RCP2.6) used by the IPCC for its 5th Assessment Report, this pathway results in the most severe global warming and climate change.” 3 For Crowsnest, AB. 49.630556ºN, 114.6925º W.

01251-BGC-C-RP-0001_01_ABC Section_Desktop Geohazards Preliminary Assessment_Rev 1

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Figure 3-2. Maximum 1-day Total Precipitation4 (Climatedata.ca, April 30, 2020).

Table 3-1. Regulated Dams Upstream of the Project (Alberta Dam Safety Map, April 30, 2020).

Alberta Dam Safety Height Capacity Dam Watercourse, KP Consequence 3 Purpose Classification (m) (x1000 m ) Unnamed, Ganske,H & Low 3.7 123.3 Recreation Mielke,R Dam Upstream of KP 2+700 Allison Creek, Allison Creek Habitat, Fish Hatchery Main Approximately Low 8.4 518 Culture, Dam 150 m before KP Recreation 0+000(1) Note: 1. Dam is located upstream of infrastructure which the proposed pipeline would tie into.

3.4. Geological Setting The Crowsnest area is in the Foreland Belt of the Canadian Cordillera, which is almost entirely underlain by sedimentary rocks. The oldest exposed rocks are carbonate and shale deposited near the ancient North American continental margin in Cambrian through Jurassic time. Between

4 Maximum 1-day Total Precipitation including historical observations (orange), historical modeled values (black/grey shading), and high emissions scenario climate change projections (RCP 8.5) (red/pink shading). The black and red lines indicate the median value of 24 climate models used to simulate historical (1950 to 2005) and projected (2006-2100) global climate in response to changing atmospheric concentrations of greenhouse gasses, while the grey and pink shaded areas show the 90th and 10th percentile bounds.

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Late Cretaceous and Paleocene time, marine and non-marine clastic rocks were deposited in a foreland basin that developed in response to right-lateral transpression and uplift of terranes accreted to the west. As the basin-fill clastic rocks were being formed, they were incorporated into a fold-and-thrust belt to form the Rocky Mountain and Foothills (Monger & Price, 1978; 2002). Fault slip and folding along west-dipping fault structures placed erosion-resistant carbonates on top of younger, relatively erodible clastic rocks, yielding a general pattern of homoclinal ridges with west-facing, moderately steep dip slopes and rugged, east-facing escarpments. The dip slopes and escarpment both are known to produce rockfall, rockslide, and rock avalanche regionally (Geertsema et al., 2010). In addition, potentially soluble bedrock may result in karst (dissolution) features and associated hazards locally (Stokes et al., 2010; Ford, 1979) while mountain-building and post-glacial tectonic activity has generated potential mineralization prone to acid-generation and faulting along with modern seismic hazard. The Pleistocene and early Holocene epochs (approximately 126,000 to 11,700 years before present) represent a time of repeated advances and retreats of glaciers across North America. Thick glaciers covered most of southeastern British Columbia during the most recent glaciation, between approximately 25,000 and 10,000 years ago. The Front Ranges were influenced by Cordilleran ice advancing from the west, montane glaciers from local peaks, and Laurentide ice advancing across the Plains (Bobrowski & Rutter, 1992). The various geohazard processes observed within the study area are consequences of the landscape formed by tectonics and glaciers. Rock avalanches occur within carbonate rocks, where west-facing dip slopes have been debuttressed by glacial and postglacial erosion, and where fault-bend and fault-propagation folds daylight in escarpments. Deposits from past rock avalanches are present around subalpine and alpine cirques at the headwaters of Tornado and Line creeks, east of Fording River; and on the east flank of Turtle Mountain, near Blairmore, Alberta. Rockslides and falls are common on high, steep escarpment faces in strong carbonate and sandstone, and where fine-grained clastic rocks have been eroded and oversteepened by glaciers, streams, and man-made excavations. Debris slides and avalanches are common on steep terrace risers, particularly along actively eroding streams. Paraglacial and contemporary erosion yields an abundance of sediment that is frequently mobilized in debris flows and debris floods, which affect alluvial fans in valley bottoms across the study area. Regional surficial geology is depicted on Drawing 02. Bedrock geology is shown on Drawing 03.

3.5. Historic Geohazard Events The main geohazard (landslide hazard) event of historic significance in the Crowsnest area was the . It was a rock avalanche which occurred in 1903 (McConnell and Brock, 1904). It comprised 30 million m3 of material which released and flowed extremely rapidly (>5 m/s) from the source at approximately 2,000 m elevation, to the valley bottom at approximately 1,300 m elevation. It largely obliterated the town of Frank, and up to 90 people may have been killed. The Frank Slide is located approximately 15 km from the ABC Section. The slide released along a

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steeply-dipping bedding plane associated with anticlinal fold (Cruden and Krahn, 1973). Similar dip-slope failures are recognized elsewhere regionally.

3.6. Background Data Each technical section lists key data inputs used for the assessments. The following general data were made available as a basis for the technical work: • LiDAR-derived hillshade image and topography provided by TC (Airborne Imaging, July 2010 vintage, 0.35 m horizontal accuracy and 0.2 fundamental vertical accuracy) • Selected air photos • Photographs and notes gathered during a routing exercise in fall of 2019 • Published surficial and bedrock geology maps • Published government and academic reports and papers.

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4.0 METHODOLOGY BY GEOHAZARD TYPE

4.1. Terrain Mapping Terrain mapping is the subdivision of the landscape into geomorphic units with similar features called terrain polygons. Criteria used to delineate polygons include unique surficial geology, landforms, deposit thickness, surface water drainage, slope stability, and geohazards. Slope stability classes I through V were subjectively assigned to each polygon by considering terrain characteristics within the polygon. Terrain mapping methods were based on guidelines described by the Resources Inventory Committee (1996) and use the terrain classification system of Howes and Kenk (1997). Data fields describing material types, drainage, and slope stability were included for all terrain polygons. Mapping was completed at a nominal scale of 1:15,000 for a 500 m wide corridor in areas of low relief or from valley wall to valley wall in high relief areas. Mapping was completed using available LiDAR and orthophoto imagery. Terrain mapping was used as an iterative and collaborative tool to support the inventory work discussed in the following sections. Drawings 04A and 04B present the current dataset for the ABC Section, and a terrain map legend, respectively.

4.2. Landslide Hazards Landslide hazards are those that involve mass movements of rock, debris, or earth. Impacts to buried pipelines or above-ground infrastructure may arise through direct impact (e.g., debris hitting the pipeline), differential ground movement (e.g., at the margins of an earth landslide), or other loading scenarios (e.g., rockslide deposit comes to rest atop a buried pipeline). The hazard types analyzed here included those listed in Table 4-1.

Table 4-1. Landslide hazard types included in this study. Landslide Type Description Rock fall Fragments or large mass of rock detach from a steep rock face and travel downslope independently with a free falling, bouncing, or rolling motion. Includes seismically triggered events. Rockslide Fragments or large mass of rock detach from a steep rock face and travel downslope rapidly as a coherent mass before breaking up with increased travel distance from the source area. Includes seismically triggered events. Rock avalanche Large coherent rock mass releases from a steep mountainside, breaking up and developing flow-like behavior and long travel distance. Includes seismically triggered events.

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Landslide Type Description Earth landslide A mass of soil or very weak, highly weathered rock that moves primarily by sliding on a basal shear surface, potentially accompanied by internal deformation. Includes all deep-seated, slowly and rapidly moving landslides in soil or very weak rock. Often associated with saturation with water. May accelerate and move suddenly several meters or tens of meters or develop flow-like behaviour. Includes earth flow/slide/spread/slump. Includes seismically triggered events. Debris A shallow layer of weak soil or weathered rock overlying more competent soil slide/avalanche or bedrock that detaches and slides rapidly down a steep slope. Debris slides/avalanches may entrain additional material as they slide down slope and can evolve into debris flows if they enter a channel with sufficient water. Includes seismically triggered events. Snow/ice avalanche Extremely rapid to rapid release of snowpack layers or seasonal/glacial ice and snow which break up and develop flow-like behaviour and long runouts. May be wet or dry. Debris flow Granular debris/water mixed flows (debris dominated) which emanate from upslope basins or existing aggraded channels and run onto lower angle terrain, forming colluvial cones and fans. Debris flood Granular debris/water mixed flows (water dominated) which emanate from upslope basins and run onto lower angle terrain, forming alluvial fans. Outburst flood Debris-rich flows in existing river network generated by sudden release and rapid drainage of upstream storage in landslide-dammed, moraine-dammed, beaver-dammed, proglacial or subglacial lakes.

4.2.1. Hazard Rating For each hazard scenario we considered the location of the source area relative to the pipeline and considered whether there was a credible chance of the geohazard, if it occurs, reaching the pipeline. This is obvious when the pipeline crosses a source area (e.g., an earth landslide), but for more remote, upslope sources (e.g., rockslide) we made a judgment based on past experience and available data to determine whether the threat to the pipeline was credible. For the current study the focus was on identifying evidence of past landslide events and potential future events in the landscape, through terrain mapping, imagery review, and examination of bare-earth terrain models. Past events of different geohazard types may have a different legacy on the landscape, meaning that evidence of past events may be more or less visible at present. For example, we might expect the deposit of a large rock avalanche to be recognizable on the landscape for many thousands of years; however, evidence of a debris slide may only persist for a few tens of years. In this study we used evidence of past events and estimated potential of future events to identify locations with a credible hazard, and to estimate the impact of each on the project. As described in Section 2.0, the three-level hazard rating approach is consistent across all hazard types. Table 4-2 describes in general how these ratings were applied. Appendix B presents the detailed rationale for classification for landslide hazards (and other types).

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Table 4-2. General application of the hazard ratings for landslide hazards. Hazard Rating Landslide hazard application Low Hazard Generally applied where potential source areas are present, but there is little evidence of past events Moderate Hazard Generally applied where source areas are recognized, and there is some evidence of past events High Hazard Generally applied where source areas are present and are active, or there is evidence for fresh or incipient events Non-credible Captures locations of interest that were deemed to not have potential to generate impacts to the pipeline

Each entry in the geohazard inventory for this study (Section 5.1) contains unique pipeline segments having relatively uniform potential impact. The entire Section was assessed for each hazard type, and only those segments with credible exposure to a given geohazard were listed in the inventory. Some segments (or parts of segments) may be exposed to more than one geohazard; in that case, each geohazard would be assessed separately.

4.3. Hydrotechnical Hazards

4.3.1. Hydrotechnical Hazard Description Hydrotechnical hazards are a class of geohazards that are related to the movement of water in and around a watercourse. Hydrotechnical hazards of a sufficient magnitude can result in an exposure or free span of the pipeline. An exposed pipeline in a watercourse may be physically impacted by an object transported in the flow, leading to pipeline failure. A pipeline free-spanning in the flow may also be subjected to hydrodynamic forces, or vortex-induced vibrations (VIV) leading to pipeline failure. It was assumed that trenchless crossing methods (e.g., horizontal directional drill) are not currently proposed for watercourse crossings. Hydrotechnical hazard mechanisms included in the scope of work result from clear-water flood flows generated by rainfall, snow melt, or a combination. Other hazard mechanisms, such as ice jams or blocked culverts have not been examined. Provincially regulated dams located upstream of the proposed pipeline are noted in Table 3-1 and shown on Drawing 05. Additional analysis may be recommended following further review, as a separate scope of work. The types of hydrotechnical hazards that were identified in the scope of work included: • Scour of the channel bed • Degradation of the channel bed • Bank erosion (pipeline alignment traverses the watercourse) • Encroachment (bank erosion where the pipeline alignment is adjacent to the watercourse) • Avulsion.

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Hydrotechnical hazards to a buried pipeline are present where the alignment either crosses, or is adjacent to, a watercourse, floodplain, or alluvial fan.

4.3.2. Hydrotechnical Hazard Mapping Objective The two key pipeline design parameters are minimum depth of cover (min. DoC) and the KP stationing that min. DoC applies to. NGTL has several standard watercourse crossing designs that will be used for the project5. Min. DoC is 1.8 m or the 100-year vertical scour depth6, whichever is greater. Min. DoC can be reduced for special circumstances: • 1.3 m for shallow, competent bedrock • 1.5 m for irrigation/drainage ditches where limited erosion potential can be demonstrated. Site-specific design is required where there is: • Evidence of bank instability, erosion, scour, shifting channel bed • Anticipated bank erosion • An outside meander bend (requires bank erosion assessment). For the deliverable herein, hydrotechnical hazard sites were classified into one of two categories based on a desktop-level, preliminary assessment of potential hydrotechnical hazards to the proposed pipeline: Low Hazard: generally stable conditions with low potential for hazardous vertical or horizontal erosion. Moderate Hazard: unstable crossing site, high energy flows with potential for hazardous vertical and/or horizontal erosion. High Hazard is reserved for very complex hydrotechnical hazard sites that would require trenchless or atypical trenched construction methods; none were observed in the ABC Section.

4.3.3. Hydrotechnical Hazard Mapping Methodology Initial watercourse crossing lists were developed by Midwest Surveys Inc. (surveyors) and Stantec Consulting Ltd. (environmental consultant) and provided to BGC on March 30, 2020, which indicated three hydrotechnical hazard sites. BGC reviewed the list and identified three additional sites. Sites were then classified as either Low or Moderate hydrotechnical hazard based on typical indicators such as those shown in Table 4-3.

5 TransCanada Design Standard Dwg No. STDS-03-ML-03-101 Rev 02, and TransCanada North Montney Mainline NPS 42 (2015) Aitken Creek Section. Dwg. No. 18142-03-ML-10-003 Rev. 03. Case B – Rock Below River Bed. 6 Based on TCPL standard watercourse crossing typical details.

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Table 4-3. Hydrotechnical hazard classification typical indicators.

Parameter Low Hazard Moderate Hazard

Stream type Low energy High energy Local Geometry Straight to gentle bend(1) Moderate(2) to 90° Bend Observed Bank None Undercut banks, slumping, erosion Erosion Alluvial Fan Absent Present Side channels Absent Wide, poorly confined floodplain with Confined Channel meander bend scars, oxbow lakes Bankfull width Narrow (<2 m) Wide Notes: 1. Typically a sinuosity < 1.5 2. Typically a sinuosity > 1.5

4.4. Seismic Hazards

4.4.1. Seismic Shaking Natural Resources Canada (NRCAN) provides reference-condition peak ground acceleration

(PGA), peak ground velocity (PGV), and peak 5%-damped spectral acceleration (Sa(T), where T is fundamental period in seconds) for a range of exceedance probabilities at 10 km spacing across Canada (Halchuk et al., 2015a). These data were prepared for the 2015 National Building Code of Canada (NBCC; National Research Council of Canada, 2015) and comprise the basis for mapping the expected distribution of strong earthquake shaking along the ABC Section. Incoming seismic waves may be amplified where they pass through near-surface soils. The potential for amplification or damping is estimated from site classes that are based on expected shear-wave velocity (Building Seismic Safety Council, 1994). In the absence of detailed subsurface information, as may be obtained through borehole drilling, we assign preliminary site class ratings based on the terrain mapping and mapped bedrock geology. Where bedrock is within 1 m of ground surface, site class is inferred from rock types mapped by Stockmal and Fallas (2015) as follows: • Class A (hard rock): intrusive and metamorphic rock; carbonate; coarse clastic sedimentary rock • Class B (rock): volcanic and fine clastic sedimentary rock. Where bedrock is >3 m below ground surface, site class is inferred from surficial material type described on project-specific terrain maps as follows: • Class C (very dense soil): basal till • Class D (stiff soil): ablation till, glaciofluvial deposits, talus • Class E (soft soil): active channel beds and bars, colluvium, lakes, lacustrine and glaciolacustrine deposits, organic deposits.

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Where bedrock is between 1 and 3 m below ground surface, classes are inferred as per Table 4-4, using the classifications of soil and rock described in the two previous bullet lists.

Table 4-4. Combination rules for rock and soil site classes where rock is between 1 and 3 m below ground surface. Rock Site Soil Site Class Class C (very dense soil) D (stiff soil) E (soft soil) A (hard rock) A B B B (rock) B B C C (soft rock) C C C

Amplification factors for each site class (National Research Council of Canada, 2015) were applied to obtain site-specific PGA values. To account for topographic effects, PGA was multiplied by 1.3 where the slope angle is between 10 and 30 degrees and 1.5 where the slope angle exceeds 30 degrees (Rathje and Bray, 2001; Ashford and Sitar, 2002; Bray and Macedo, 2019). This method was applied to earthquake-triggered landslides but omitted from the liquefaction assessment, as liquefiable terrain is confined to low-angle valley bottoms.

4.4.2. Liquefaction Liquefaction can occur where loose, saturated soils are subjected to strong earthquake shaking, causing a sudden increase in pore-water pressure, decrease in effective stress, and loss of shear strength. Liquefied soils can experience vertical settlement or large horizontal permanent ground displacement (PGD) as lateral spreads and flows. Liquefaction susceptibility was assigned to terrain polygons following a system proposed by Quinn et al. (2015). Liquefaction hazard was estimated by combining liquefaction susceptibility and PGA experienced at site (i.e., reference-condition PGA multiplied by site-class amplification factor) as per Table 4-5.

Table 4-5. Relative liquefaction hazard derived from liquefaction susceptibility and PGAsite. Amplified 1:2,475 Liquefaction susceptibility PGA (PGAsite) None Low Moderate High ≥0.2g None Low Moderate High 0.1-0.2g None Low Low Moderate <0.1g None Low Low Low

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4.4.3. Earthquake-Triggered Landslides

7 Landslides can occur where PGA experienced in an earthquake (PGAsite ) exceeds a slope’s

critical acceleration (ac), which is the horizontal acceleration required to reduce factor of safety against sliding below unity. This preliminary assessment employs generalized relationships between geology, expected saturation, slope angle, and critical acceleration developed by Wieczoriek et al. (1985) and Wilson and Keefer (1985). The generalized methodology omits structural, lithologic, and topographic details that might impact local seismic stability conditions; thus, the interpreted landslide potential on specific slopes is subject to considerable uncertainty, but the distribution of mapped hazard should give insight into the regional prevalence of earthquake-triggered landslide potential. Many details that are necessarily omitted in this assessment of earthquake-triggered landslide potential are incorporated into the assessment of static landslide hazard; combined, they should provide sufficient detail for hazard identification. Mapped soil units (from project-specific terrain maps) and bedrock (from Stockmal & Fallas, 2015) are generalized into strongly cemented rocks (Group A), weakly cemented rocks and soils (Group B), and argillaceous rocks and soils, including existing landslides (Group C). Where bedrock is 1 m deep or more, the geologic group assignment is based on primary surficial material (Table 4-6); otherwise, the assignment is based on bedrock type (Table 4-7). Critical

acceleration, ac, is determined as shown in Figure 4-1.

Table 4-6. Geologic groups by surficial material. Symbol Description Geologic Group A Anthropogenic C C Colluvium C Aeolian sand B E Loess C F Fluvial B FA Active Fluvial B FG Glaciofluvial B L Lacustrine C LG Glaciolacustrine C M Till B O Peat C R Bedrock See Table 4-5

7 For earthquake-triggered landslides, PGAsite incorporates amplification factors for both site class and topography.

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Table 4-7. Map units, lithologic descriptions, and interpreted geologic groups along the ABC Section. Geology from Stockmal and Fallas (2015). Map Unit Lithologic Description Geologic Group Wapiabi and Telegraph Creek formations Shale, siltstone, sandstone, limestone, C bentonite Virgelle, Deadhorse Coulee, and Pakowki Sandstone, shale, mudstone, coal, B formations, and Belly River Group limestone, bentonite Flathead, Gordon, Elko, and Windsor Dolostone, limestone, mudstone, shale, A Mountain formations sandstone, conglomerate Fairholme Group and Sassenach and Alexo Limestone, dolostone, shale, siltstone, A formations sandstone, breccia Palliser Formation Limestone, dolostone, anhydrite A Exshaw and Banff formations Limestone, siltstone, mudstone, chert, B shale Livingstone Formation Limestone, dolostone A Mount Head Formation Limestone, dolostone, shale B Etherington Formation Dolostone, limestone, chert, sandstone, A shale, siltstone

0.5

0.4

0.3

0.2 CRITICAL ACCELERATION ACCELERATION (g) CRITICAL -

Ac 0.1

0 0 5 10 15 20 25 30 35 40 45 50 SLOPE ANGLE (DEGREES)

A-DRY A-WET B-DRY B-WET C-DRY C-WET

Figure 4-1. Critical acceleration versus slope angle for three geologic groups and two groundwater conditions. From Wilson and Keefer (1985).

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Earthquake-triggered landslide potential is classified based on the ratio between ac and PGAsite over a range of exceedance probabilities as follows:

• Class 5 if ac/(1:100 PGAsite) ≤1.0

• Class 4 if ac/(1:475 PGAsite) ≤1.0

• Class 3 if ac/(1:1,000 PGAsite) ≤1.0

• Class 2 if ac/(1:2,475 PGAsite) ≤1.0

• Class 1 if ac/(1:2,475 PGAsite) >1.0 Earthquake-triggered landslide hazard was classified based on the distribution of landslide potential as follows: • No Hazard present where pipeline segments cross only Class 1 rated terrain. • Low Hazard where pipeline segments cross mostly Class 2 and Class 3 terrain, and Class 4 and Class 5 terrain is absent around the RoW. • Moderate Hazard where Class 5 terrain is absent and Class 4 terrain comprises less than 50% of the terrain around the RoW. • High Hazard where the pipeline crosses at least 50% Class 4 and Class 5 rated terrain.

4.4.4. Surface Faulting Surface faulting refers to PGD that occurs at the ground surface along the trace of a fault that slips in an earthquake. In this desktop assessment, we looked for potentially active surface faulting by comparing the locations of historical earthquakes (Halchuk et al., 2015b; Mueller, 2018; Stern et al., 2018; NRCAN, 2020; U.S. Geological Survey, n.d.) and topographic lineaments (visible on available LiDAR, orthophoto, DEM, and Google Earth™ data) against mapped bedrock faults (Price, 2013; Stockmal & Fallas, 2015). We also reviewed published inventories of known and suspected Quaternary faults by BC Hydro (2012) and U.S. Geological Survey and Montana Bureau of Mines and Geology (USGS-MBM, n.d.). Surface faulting hazard was assigned as follows: • High Hazard where Holocene faulting is suspected: ○ Pronounced topographic lineaments expressed in late- or post-glacial deposits that follow a mapped bedrock fault or cannot be explained by another credible landscape-forming process ○ Historical seismicity following a topographic lineament or mapped fault. • Moderate Hazard where Quaternary faulting is suspected: mapped bedrock faults with topographic lineaments expressed in Pleistocene (glacial) deposits but masked by Holocene (postglacial) deposits. • Low Hazard along interpreted pre-Quaternary bedrock faults or those masked by Pleistocene (glacial) deposits. • No Hazard present where there are no mapped faults, fault-related lineaments, or aligned historical earthquakes.

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4.5. Subsidence Hazards Subsidence hazards include the vertical movement, collapse, or loss of foundation soils due to some underlying condition, both geological and anthropogenic. The hazard types analyzed here included those listed in Table 4-8.

Table 4-8. Subsidence hazard types included in this study. Geohazard Type Description Karst subsidence Vertical movement, collapse or loss of foundation soils due to presence of subsurface voids, caves, caverns in soluble bedrock. Mine subsidence Vertical movement, collapse or loss of foundation soils due to the presence of subsurface mine workings. Thick compressible soils Vertical movement caused by the settling of a compressible layer. Fluid-withdrawal Differential vertical movement due to hydrocarbon extraction or subsidence groundwater withdrawal (high capacity water wells can cause widespread subsidence) nearby.

4.5.1. Hazard rating The pipeline alignment was evaluated for the presence of the required conditions for each subsidence hazard (e.g., soluble bedrock for karst hazard). The primary source of information was topography, terrain mapping and published geological reports and maps (Ford, 1979; Stokes et al., 2010). Where the required condition was met, the hazard was rated according to the three-level system described in Section 2.0. The hazard ratings for subsidence are based on evidence for past or on-going subsidence, given that the required condition is (or may be) present. The LiDAR hillshade models are the key input for this, as we would expect some expression in the landscape of past or active hazardous subsidence. Table 4-9 describes in general how these ratings were applied. Appendix B presents the rationale for classification of subsidence hazards (and other types).

Table 4-9. General application of the hazard ratings for subsidence geohazards. Hazard Rating Subsidence geohazard application (Non-credible) Required condition not met Low Hazard Generally applied where the required condition is (or may be) present Moderate Hazard Generally applied where there is evidence of past subsidence events High Hazard - Generally applied where active subsidence is recognized

Each entry in the geohazard inventory for this study (Section 5.1) contains unique pipeline segments having relatively uniform potential impact. The entire section was assessed for each hazard type, and only those segments with credible exposure to a given geohazard were listed in the inventory. Some segments (or parts of segments) may be exposed to more than one geohazard; in that case, each geohazard would be assessed separately. No analysis of a governing hazard was conducted as part of this work.

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4.6. Geotechnical Hazards Geotechnical hazards are those which could lead to foundation or other shallow instability issues, or reduced soil restraint on a buried pipeline. These are typically related to the interaction between naturally occurring geological conditions and ground disturbance through pipeline construction. The hazard types analyzed here included those listed in Table 4-10.

Table 4-10. Geotechnical hazard types included in this study. Geohazard Type Description Problematic (Expansive or Soils with a propensity to swell or collapse with changes in water content, collapsible) soils and associated stability challenges. Permafrost degradation Unstable conditions induced by thawing of permafrost. Peat/organic soils Organic soils and associated poor foundation conditions, including buoyancy and subsidence issues.

4.6.1. Hazard rating The pipeline alignment was evaluated for the potential presence of the required conditions for each geotechnical hazard (e.g., presence of permafrost). The primary sources of information were terrain mapping and published geological reports and maps (e.g., Geertsema et al., 2010). Anywhere with a credible potential for the condition to be present, the hazard was rated according to the three-level system described in Section 2.0. The hazard ratings for subsidence are based on confidence or likelihood that the condition is present; it is implicitly assumed that some sort of site-specific management will be required wherever the conditions are met. Table 4-11 describes in general how these ratings were applied. Appendix B presents the rationale for classification for geotechnical hazards (and other types).

Table 4-11. General application of the hazard ratings for geotechnical hazards. Hazard Rating Geotechnical hazard application Low Hazard Generally applied where the required condition is unlikely to be present Moderate Hazard Generally applied where the required condition may be present High Hazard Generally applied where the required condition is known to be present Non-credible Required condition not present

Each entry in the geohazard inventory for this study (Section 5.1) contains unique pipeline segments having relatively uniform potential impact. The entire section was assessed for each hazard type, and only those segments with credible exposure to a given geohazard were listed in the inventory. Some segments (or parts of segments) may be exposed to more than one geohazard; in that case, each geohazard would be assessed separately.

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4.7. Geochemical Hazards Geologic units can host mineral compositions that are more ‘permissive’ of producing acid rock drainage (ARD) and/or metal leaching (ML) conditions if bedrock is exposed or disturbed during pipeline construction. Specifically, ARD refers to the generation of acidity from the oxidation of sulphide minerals upon exposure to oxygen and water. In general, pyrite (FeS2) is the most common sulphide mineral present in the environment; however other sulphide minerals may oxidize and produce acidity (e.g., pyrrhotite Fe1-XS; chalcopyrite CuFeS2).

Carbonate minerals (e.g., calcite CaCO3; dolomite CaMg(CO3)2) can readily neutralize acidity generated from sulphide oxidation and buffer pH values to near neutral conditions. Other minerals (e.g., silicates, oxides) also bear a neutralization capacity, but typically react at a much lower rate relative to sulphide oxidation or carbonate dissolution and buffer to lower pH conditions. The ratio or relationship between acid-generating and acid-buffering minerals within rock units can help identify those assemblages that have the potential for producing ARD/ML conditions. Metal leaching may occur as a result of sulphide oxidation and/or dissolution of associated minerals. Although many metals are more mobile under acidic pH conditions (e.g., Co, Cu, Pb), some metals and metalloids are more mobile at neutral pH conditions (e.g., As, Mo, Se). If released, both acidic-pH and neutral-pH mobile elements may cause adverse impacts to a receiving environment. This assessment describes ‘permissive’ geologic units as those units anticipated to contain acid-generating minerals in proportions that may outpace or overwhelm the proportion of acid-neutralizing minerals and/or have the potential to release metals at significantly higher concentrations relative to site-specific background levels. In this desktop assessment, the mineral composition of a geologic unit and the alignment’s proximity to known anomalous mineral occurrences are used to assess the potential for ARD and/or ML conditions during construction. These methods are discussed in the following subsections (Sections 4.7.1 to 4.7.3), with results presented in Section 5.6. Guidance for the desktop approach used in the assessment is derived from several documents, as listed below, and are conducted on a site-specific basis. • Policy for Metal Leaching and Acid Rock Drainage at Mine Sites in British Columbia (British Columbia Ministry of Energy and Mines (BCMEM), 1998) • Prediction Manual for Drainage Chemistry from Sulphidic Geologic Materials (Mine Environmental Neutral Drainage (MEND), 2009) • Global Acid Rock Drainage (GARD) Guide (INAP, 2012).

4.7.1. Geologic Unit Permissive Likelihood Geologic units intersected along the proposed ABC Section were delineated using KPs and UTM coordinates (see Drawing 03). The geologic units intersecting the alignment and their lithologic description were identified using publicly available geological maps of Alberta (Stockmal and Fallas, 2015) and satellite imagery visualization software (i.e., Google Earth).

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BGC established the following qualitative criteria to classify a geologic unit as having a “high”, “moderate,” “low,” “minimal” or “unknown” likelihood to be permissive of ARD/ML conditions, based on its lithologic description, which is applied in this assessment: • High: Assemblages containing pyritic occurrences or coal. Pyrite is known to be locally associated with coal seams or units. • Moderate: Shale or shaley interbedded assemblages. Pyrite, or sulphides, are commonly found along bedding planes of finer-grained sediments (e.g., shale) and may be present. Units known to contain porphyry or skarn assemblages. • Low: Units containing both shaley units and carbonate sequences. Carbonate-rich material provides neutralization capacity that may buffer acidity generated from sulphides that may be associated with finer-grained assemblages. • Minimal: Units comprising mostly carbonate assemblages with lesser silicate rock types. • Unknown: Units typically comprising igneous material, without mention of acid-generating and/or acid-neutralizing carbonate minerals.

4.7.2. Mineral Occurrences Mineral occurrences were identified from the Alberta Department of Energy Metallic and Industrial Minerals Activity Interactive Map8. The occurrences were highlighted as potentially ‘permissive’ for ARD/ML conditions if located within an arbitrary 2 kilometre (km) boundary on either side of the alignment, for a total of 4 km width. Mineral occurrences are typically associated with sulphide-bearing rocks, which can undergo sulphide oxidation, release metals and generate acidity. However, other mineral occurrences are documented in this database, such as industrial minerals (e.g., limestone, phosphate). A slightly wider ‘corridor of interest’ of 10 km on either side of the alignment (for a total of 20 km) was applied to those mineral occurrences referring to operational and/or closed mine developments. These boundaries are similar to those applied in previous desktop pipeline assessments (e.g., MESH, 2006; AMEC, 2014; TMEP, 2015).

4.7.3. Desktop Geochemical Hazard Rating A desktop geochemical hazard rating, developed by BGC, combines the geologic unit’s permissive likelihood with the presence of sulphide, coal or metal-bearing mineral occurrences near the proposed alignment (i.e., excludes industrial mineral occurrences such as limestone, etc.) to assess the alignment’s ARD/ML potential. Based on these inputs, alignment segments are identified as having a “high”, “moderate”, “low”, or “minimal” geochemical hazard rating, as listed below and shown in Figure 4-2: • High Hazard: Geologic units with numerous mineral occurrences and unknown, low, moderate or high permissive likelihood characterization. This classification also includes units with a high permissive likelihood and one or two mineral occurrences.

8 https://www.arcgis.com/apps/webappviewer/index.html?id=cfb4ed4a8d7d43a9a5ff766fb8d0aee5

01251-BGC-C-RP-0001_01_ABC Section_Desktop Geohazards Preliminary Assessment_Rev 1

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• Moderate Hazard: High permissive likelihood units with no documented mineral occurrences. Geologic units with one or two mineral occurrences and unknown, minimal, low and moderate permissive likelihood. • Low Hazard: Geologic units with low or unknown permissive likelihood and no mineral occurrences. • Minimal Hazard: Geologic units with minimal permissive likelihood and no mineral occurrences.

Geologic Unit ‘Permissive’ Likelihood High Moderate Low or Unknown Minimal

>2 High High High Moderate

1-2 High Moderate Moderate Moderate Mineral Moderate Occurrences 0 Moderate Low Minimal

Figure 4-2. Geochemical hazard rating criteria.

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5.0 RESULTS AND RECOMMENDATIONS Results are presented in the Appendices C to H and Drawings 05 to 09, as referenced in the section below. In the drawings, only the highest rated hazard is shown in the case of overlap between hazard subtypes.

5.1. Landslide Hazards A total of 14 segments were identified with credible exposure to geohazard threats. All of the landslide hazard types are represented. All but one of these are located in the Phillipps Pass area, beyond KP 3+400. No sites were rated High Hazard. The landslide hazard sites are summarized in Table 5-1 and detailed in Appendix C and Drawing 06.

Table 5-1. Potential landslide hazard inventory. Geohazard ID KP From KP To Hazard Type Hazard Class C-L-01 2+650 2+850 Outburst Flood Low C-L-02 3+100 3+225 Rockfall Low C-L-03 3+400 3+500 Rockfall Moderate C-L-04 3+400 5+211 Snow avalanche Low C-L-05 3+500 3+535 Rockfall Moderate C-L-06 3+875 3+925 Rockfall Moderate C-L-07 4+075 4+200 Rockfall Low C-L-08 4+200 4+380 Rockfall Moderate C-L-09 4+380 4+610 Rockfall Moderate C-L-10 4+380 4+575 Rockslide Low C-L-11 4+475 4+675 Rock avalanche Moderate C-L-12 4+530 4+600 Debris flow Low C-L-13 4+600 5+211 Debris flow Moderate C-L-14 4+775 5+211 Debris slide Moderate

There is a single moraine-dam outburst flood hazard identified in this Section. That dam should be visited, and the existing drainage channel evaluated for signs of excess erosion or downcutting, while the dam itself should be mapped for signs of distress and seeps or piping failures. It is unlikely that these will be present, but this assertion can be confirmed with minimal field mapping effort. The rockfall, rockslide, and rock avalanche hazard segments should be reviewed in the field as a group, which would likely require source area review by helicopter and some field mapping of past deposits. Key tasks would be to confirm the potential for these events and to evaluate the potential reach and impact of events releasing from specific source areas.

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Snow avalanches generally do not pose a threat to buried infrastructure. Construction safety should be managed by a formal avalanche safety plan (ASP) developed by an avalanche professional. Above-ground infrastructure such as valves may be vulnerable to snow avalanche impacts and should be assessed once locations and layouts are finalized. Structural protection is the most common approach to mitigation. A steep creek/debris flow specialist should be involved in subsequent field review and analysis for debris flow/flood. Field mapping and basin characterization would be required to further refine the assessment and to develop any mitigation recommendations or designs. Debris slide scars identified in this study should be reviewed in the field to confirm that this is in fact the process by which they formed. It is possible that these features are related to vegetation growth variations along bedrock outcrops or they may be snow avalanche paths. Buried pipelines in the deposition zone of debris slides are mostly invulnerable in any case, which means that a more detailed field review of slope geometry along is an important next step.

5.2. Potential Hydrotechnical Hazard Sites Of the six potential hydrotechnical hazard sites identified on this Section, two were classified as Low hydrotechnical hazards, while the remaining were classified as Moderate hydrotechnical hazard. The potential hydrotechnical hazard sites are summarized in Table 5-2 and detailed in Appendix D and Drawing 05.

Table 5-2. Potential hydrotechnical hazard inventory. Geohazard ID KP Hazard Type Hazard Class C-H-1 0+400 Crossing Moderate C-H-2 2+190 Crossing Moderate C-H-3 * 2+671 Crossing Low C-H-4 3+521 Crossing Low C-H-5 3+800 Encroachment Moderate C-H-6 5+200 Encroachment Moderate * Indicates environmental field investigation data collected by Stantec (Personal Communication, received from NGTL on May 1, 2020) was available for this site. As LiDAR is available for the corridor and all watercourses are ephemeral, no sites are recommended for bathymetric survey.

5.3. Seismic Hazards The ABC Section is within a region with the highest seismic hazard in Alberta and the highest in western Canada away from the west coast of British Columbia. USGS-MBM (n.d.) map several strands of the Mission fault around Flathead Lake, MT, about 160 km south of the ABC Section and ascribe latest Quaternary (<15,000 years old) ages to them. The Quaternary (<1.6 million years old) Swan and South Fork Flathead faults are mapped east

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of Flathead Lake, extending to 135 km south of the ABC Section. BC Hydro (2012) identifies three normal fault earthquake sources (i.e., assumed Quaternary or younger age) continuing northward, as follows: • The Whitefish fault from the Mission fault to about 24 km north of the international boundary along the Galton Range front, on the east side of the Rocky Mountain Trench. The mapped fault source passes 45 km west of the ABC Section. • The Flathead fault, which follows the Lewis Range front north along the east side of the Flathead River valley. BC Hydro (2012) extends the suspected-active fault source to about 13 km north of the international boundary, or to 55 km south of the ABC Section. Price (2013) and Stockmal and Fallas (2015) map the structure to the Flathead River headwaters, 35 km south of the ABC Section, where it bends west into the Michel Creek valley to pass 9 km west of the Section; whereas a system of west-dipping thrust faults, including the Lewis Thrust, continues along strike toward the Section. Price (2013) maps the Flathead fault cutting the Lewis fault, whereas Stockmal and Fallas (2015) interpret them as merging. Neither Price (2013) nor Stockmal and Fallas (2015) describe Quaternary activity along these faults. • The Nyack fault, mapped along the west side of the Flathead River valley to about 16 km south of the international boundary, or about 85 km south of the ABC Section. BC Hydro (2012) interprets this fault as antithetic to, and thus coeval with, the Flathead fault. The absence of known mapped Quaternary faults north of those mapped by BC Hydro (2012) and USGS-MBM (n.d.) could imply that no faults closer to the ABC Section have experienced late- or post-glacial surface ruptures, that faults have slipped since deglaciation but have not manifested detectable surface traces in the landscape, or that fault traces are undetected due to a lack of investigative effort. Available LiDAR and orthophoto data around the ABC Section shows mapped bedrock faults truncated by Pleistocene (glacial) and Holocene (postglacial) deposits; this implies that the latest activity pre-dates the latest Cordilleran glaciations and is at least pre- Holocene. Historical earthquakes have clustered around Flathead Lake, 160 km south of the ABC Section, with recorded moment magnitudes (M) up to 5. Halchuk et al. (2015b) report an M 4.7 earthquake in 1984 along the BC-AB border, 10 km east of the Flathead fault trace mapped by Price (2013), 17 km north of the Flathead fault source mapped by BC Hydro (2012), and 48 km south of the ABC Section. Otherwise, within about 200 km of the ABC Section, earthquakes have been sparse with M generally less than 4.0. Historical seismicity is not aligned with mapped bedrock faults around the ABC Section. The Rocky Mountain Foothills, east of the ABC Section, have experienced induced seismicity related to oil and gas production. At Cardston, events up to M 2.8 are interpreted by the Alberta Geological Survey (n.d.) as due to hydraulic fracturing. The Turner Valley cluster, 110 km to the northwest, includes events up to M 3.5, interpreted by Barnova et al. (1999) as induced by high-pressure wastewater injection. Similar clusters of induced seismicity have occurred farther north in the Rocky Mountain Foothills around Rocky Mountain House (Wetmiller, 1986; Baranova et al., 1999) and (Schultz et al., 2014).

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Reference-condition PGA at 1:2,475 annual frequency of exceedance (i.e., the NBCC design value) is 0.126 g (Halchuk et al., 2015a). Figure 5-1 and Figure 5-2 present the reference-condition PGA hazard curve and uniform hazard response spectra respectively.

1.E+00

1.E-01

1.E-02

1.E-03 Annual exceedance probability exceedance Annual

1.E-04 0.001 0.01 0.1 1 Peak ground acceleration (g)

Figure 5-1. Reference-condition (site class C) PGA hazard curve.

0.3

0.25

0.2

0.15 damped spectral spectral damped - 0.1 acceleration (g) 0.05 Peak 5% Peak 0 0 1 2 3 4 5 Period (s)

1:2,475 1:1,000 1:475 1:100

Figure 5-2. Reference-condition (site class C) uniform hazard response spectra for 1:100, 1:475, 1:1000, and 1:2,475 annual exceedance probabilities. Reference-condition (site class C) uniform hazard response spectra for 1:100, 1:475, 1:1,000, and 1:2,475 annual exceedance probabilities.

Appendix E lists 14 earthquake triggered PGD hazards (liquefaction, landsliding, and surface faulting) along the ABC Section. Fault crossings are tabulated as single locations (i.e., same from and to location along the pipeline); however, fault zones might be tens to hundreds of metres wide on the ground. Earthquake hazards along the pipeline are illustrated in Drawing 07.

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Ground reconnaissance is recommended at high and moderate hazard crossings to check assumed deposit types, soil textures and densities, local topography, and groundwater conditions. Site-specific investigations of liquefaction triggering and ground displacement potential may be recommended where loose, saturated deposits occur on topography that favours lateral spreads or flow slides. Site-specific investigations of landslide triggering and ground displacement potential may be recommended where the field reconnaissance confirms the desktop-interpreted hazard. These investigations might include subsurface geotechnical investigations and numerical modelling.

5.4. Subsidence Hazards Two segments of karst hazard were identified; together they cover the entire Section (Table 5-3 and Appendix F, Drawing 08). They differ in specific bedrock type, but also in thickness of surficial cover over bedrock, which is much greater in the eastern portion of the Section (C-S-01), whereas the western portion of the Section (C-S-02) is aligned over exposed or thinly covered bedrock. Karst features are not recognized in the eastern portion of the Section; however, karst features are mapped on the upper reaches of Mt. Phillipps, above the western end of the Section (Ford, 1979), and at least one mapped spring reaches the valley bottom west of the Section end. In addition, Phillipps Lake, located approximately 400 m beyond the end of the Section is itself likely occupying a karstic sinkhole.

Table 5-3. Potential subsidence hazard inventory. Geohazard ID KP From KP To Hazard Type Hazard Class C-S-01 0+0 4+600 Karst Low C-S-02 4+600 5+211 Karst Moderate

While no clear evidence of karst subsidence was identified along the Section, the presence of soluble bedrock underlying the entire Section and the recognized karst features nearby, means that the potential to encounter karst subsidence should be considered at all project phases. A shallow geophysical survey may provide valuable information on this hazard, particularly anywhere that voids are identified. No potential subsidence due to mine workings or fluid withdrawal were identified in this section.

5.5. Geotechnical Hazards Two segments of geotechnical hazards were identified, both associated with peat/organic soils (Table 5-4 and Appendix G, Drawing 09). These segments span several wetland areas and organic soil intersections identified in terrain mapping. No permafrost or problematic soils (Appendix A) were identified in this assessment.

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Table 5-4. Geotechnical hazard inventory. Geohazard ID KP From KP To Hazard Type Hazard Class C-G-01 0+0 1+400 Peat/organic soils Moderate C-G-02 2+500 2+530 Peat/organic soils Moderate

Challenging construction and foundation conditions may be encountered in these segments. A field review would likely allow for better characterization of these conditions. These areas are currently planned for further investigation as part of the buoyant soils field program.

5.6. Geochemical Hazards The proposed section alignment in the Crowsnest Pass region intersects six geologic units and 20 formations (Table 5-5, Appendix H). These units include Upper Devonian to Mississippian marine ramp carbonate assemblages, Middle Cambrian calcareous sediments and, Lower Cretaceous marine and terrestrial clastic rocks. The individual descriptions for each formation are provided in Table 5-5. Based solely on the lithologic descriptions, the assemblages along the ABC Section are labeled with permissive likelihood as: high from KP 1.6 to KP 3.5, primarily due to the occurrences of bituminous coal, and low for the remainder due to the presence of carbonate, argillite and shaley units (Table 5-5). There are numerous mineral occurrences documented in Alberta within 2 km of the Crowsnest alignment, as noted in Table 5-5. Notably, there are 22 limestone mineral occurrences from KP 3.1 to KP 5.2. This region is also identified as a karst-forming unit by Ford (1979). Although karst presence is not suggestive of an ARD/ML concern, there does exist the potential for karstic features to influence other geohazards identified as part of this section’s overall desktop assessment. The overall desktop geochemical hazard rating for the ABC Section is shown in Drawing 10 and characterized as: moderate from KP 0 to KP 3.5 (i.e., 68% of the alignment) and low for the remaining 32% of the alignment (i.e., KP 3.5 to KP 5.2).

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Table 5-5. Desktop Geochemical Hazard Assessment for the ABC Section, Alberta.

KP Description Mineral Occurrences Desktop Geologic Unit1 From- Geologic Geochemical To Lithology2 Permissive Nearest KP Commodity4 Hazard Rating5 3 (km) Likelihood Wapiabi and Wapiabi Formation: shale, siltstone, sandstone and Telegraph Creek calcareous sandstone beds. Formations 0.0 - 1.6 Telegraph Creek Formation: shale: silty or sandy. Low 0 Sulphur (M32443) Moderate (KWpT) sandstone, siltstone; nodular; bentonite; limestone (Lower Cretaceous) concretions. Virgelle Formation: sandstone: quartz arenite, locally calcareous or iron-bearing, contains small rusty concretions. Deadhorse Coulee Formation: sandstone; shale: silty; Virgelle, mudstone and shale: carbonaceous, minor coal. Clay/Shale 2.5 Deadhorse Coulee Pakowki Formation: mudstone and shale, minor sandstone. (T177498) and Pakowki Belly River Group Formations and 1.6 – 3.5 Drywood Creek Formation: shale, carbonaceous, High Moderate Belly River Group sandstone, minor coal. (KVB) Lundbreck Formation: mudstone and shale, locally (Lower Cretaceous) carbonaceous, caliche nodules and calcrete; sandstone, limestone, occurs as concretions and caliche hardpans. Clay/Brick; 3.3 Connelly Creek Formation: sandstone, mudstone and Dolomite (C21234) shale; rare limestone: bivalve or gastropod coquina. Flathead Formation: sandstone, quartz arenite, weathering, Flathead, Gordon, conglomerate: quartzite-pebble. Elko and Windsor Gordon Formation: shale: micaceous; sandstone: glauconitic Mountain 3.5 – 3.6 or limonitic, quartzose, interbedded with shale; limestone. Low - - Low Formations (CFW) Elko Formation: dolostone, limestone; minor mudstone: (Middle Cambrian) calcareous, Windsor Mountain Formation: dolostone; minor limestone. Fairholme Group 2 dolomite Mount Hawk Formation: limestone: argillaceous, micritic 3.7 occurrences Fairholme Group to finely crystalline, calcareous shale, minor mudstone (C20917; C21311) and Sassenach Perdrix Formation: calcareous shale, bituminous. Dolomite (C21662); Low and Alexo 3.6 – 4.3 Maligne Formation: limestone, commonly silty 3.8 Phosphate Low

Formations (DFSA) Sassenach Formation: sandstone, siltstone, dolostone, (C161892) (Upper Devonian) limestone, silty and argillaceous. 2 limestone Alexo Formation: dolostone and limestone, silty and 4.0 occurrences argillaceous. (C12643; C12513) Clay-Brick and 4 Palliser Formation limestone (DP) Limestone, argillaceous, commonly cherty with minor 4.3 – 4.9 Low 4.5 occurrences Low (Upper Dev. – limestone, minor bedded dolostone/limestone (T39163; C14891; Mississippian) C12991; C13078)

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KP Description Mineral Occurrences Desktop Geologic Unit1 From- Geologic Geochemical To Lithology2 Permissive Nearest KP Commodity4 Hazard Rating5 3 (km) Likelihood 2 limestone 5.1 occurrences (C5496; C11540) Exshaw Formation: carbonaceous shale, silty, siltstone, 14 limestone Exshaw and Banff dolomitic and calcareous; minor limestone: argillaceous, occurrences Formations cherty. (C15138; C8251; (DMEB) 4.9 – 5.2 Low Low Banff Formation: lime mudstone to skeletal packstone, C6256; C8095; (Upper Dev. – variably argillaceous and cherty, siltstone and mudstone: C5993; C9299; Mississippian) 5.2 variably calcareous; shale. C9534; C8896; C8967; C6531; C10280; C10215; C10533; C9837) Notes: KPs reference the April 9, 2020 alignment. 1. Units identified from Stockmal and Fallas (2015). Bracketed information represents the geologic age of the unit. 2. Lithologic descriptions provided in Stockmal and Fallas (2015). 3. Refer to Section 4.7.1 for description of criteria used to assess permissive likelihood. 4. Mineral occurrence reference number presented in brackets 5. Desktop Geochemical Hazard Ranking does not include mineral occurrences that are not sulphide, coal or metal -bearing, refer to Section 4.7.3.

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5.7. Uncertainties The desktop geohazards assessment has produced inventories of potential hazard sites. Desktop-level assessments necessarily rely on whatever data are available, and do not have the benefit of directed, site-specific field review or investigations. This results in recognized uncertainties in the assessment results, which are typically addressed at later stages in the project. Common across all geohazard types in this assessment are uncertainties related to accuracy (and scale or resolution) of topographic data, imagery, geological mapping, and published reports. Given these uncertainties, the desktop assessment is conducted at a coarse scale, with the intention to identify and inventory potential hazards, and focus on higher priority hazard locations at a more detailed level in later project phases. Aside from these general uncertainties, several hazard-specific uncertainties include the following.

5.7.1. Landslide Hazard Assessment The landslide geohazard assessment relies heavily on the terrain mapping and the available topographical and terrain data. Neither of these have been checked in the field, and it is possible that some hazards have been misidentified or not identified. Field review is a critical step in reducing this uncertainty and refining the assessment.

5.7.2. Hydrotechnical Hazard Assessment The hazard class assigned to each of the hydrotechnical hazards is preliminary and potentially conservative. The assessment relied upon limited data to infer a distinction between Low Hazard and Moderate Hazard classes. The standard watercourse crossing designs provided by TCPL require a detailed analysis for all watercourse crossings regardless of Hazard class. If the alignment of the proposed pipeline is revised, the observations made as part of this desktop assessment may change, potentially affecting the hazard rating. Potential hydrotechnical hazard sites are identified by a single point, however the hazard extends up and down the chainage from the point to include the width of the channel, floodplain, or alluvial fan. The length of the hazard will be evaluated as part of the future work (Section 6.2).

5.7.3. Seismic Hazard Assessment The assessment of liquefaction potential relied upon project-specific terrain maps. In the absence of reliable groundwater data, all soils were assumed to be saturated. However, the degree of saturation is a key input into liquefaction triggering. Furthermore, at this stage, the objective was to identify terrain that might liquefy, whereas pipeline damage is typically a function of the magnitude of large PGD. Not all liquefied soils will flow or spread; other local topographic and geologic conditions, which typically require field verification, are required. By assuming saturation and limiting the assessment to triggering potential (not PGD potential), the results are inherently conservative with respect to pipeline integrity.

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The assessment of landslide potential relied upon regional, coarse-resolution digital elevation models, assumed saturation conditions, and binning geological units into broad strength classes. The assessment excluded consideration of local structural features and strength heterogeneity which in practice would have a large impact on the results. Thus, the assessment is meant only as a rough guide to the kinds of terrain that might experience earthquake-triggered landslides, and not as a definitive statement on whether a particular piece of terrain will slide in an earthquake. The assessment of surface faulting potential relied upon available earthquake catalogs, published inventories of Quaternary faults, and published geological maps. Owing to the distribution of populations and seismograph stations in space and time, the earthquake record is necessarily limited: no earthquakes that might have occurred before about 1890 are catalogued, and smaller-magnitude earthquakes may have eluded detection back when seismographs were less common and less sensitive. Thus, the utility of the historical earthquake record in identifying potentially active faults is limited. Paleoseismology – the use of the geological record to study historic and prehistoric earthquakes – has been deployed over the past few decades in seismically active regions but has not been a priority of the geological research community in Canada until the past few years. Thus, the absence of mapped Quaternary faults around the study area might not be because the Quaternary faults themselves are not there; rather, it may simply be because nobody has looked for them. The glaciated landscape of western Canada presents unique challenges to paleoseismic investigations, particularly around the study area where tectonic strain rates are low: landforms take time to develop through repeated events, but the time span since glaciation (when the landscape slate was essentially wiped clean) has been relatively short. Furthermore, dense forest cover obscures small landforms, further compromising detectability. In recent years, LiDAR has proven to be an effective tool in identifying small surface-faulting landforms in vegetated and glaciated terrain.

5.7.4. Subsidence Hazard Assessment The subsidence hazard assessment relied on terrain, geological and karst mapping, and evidence of subsidence on the landscape. The key uncertainty is probably related to the latter: it’s not certain that all existing or incipient subsidence would be detected visually. Key indicators are often best observed on the ground through field review, expressed as subtle evidence of distress.

5.7.5. Geotechnical Hazard Assessment The geotechnical hazard assessment relied heavily on the terrain mapping, which has not been field-checked and may not have captured every potential hazard. Some field fitting may be required during construction to manage geotechnical hazards as they arise where not identified in the desktop study or field review stages of the project.

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5.7.6. Geochemical Hazard Assessment The desktop ranking to assess geochemical hazards is dependent on the type of geologic units the proposed route intersects and the number of mineral occurrences located nearby. If the alignment of the ABC Section is revised, the observations made as part of this desktop assessment may change, potentially affecting to the geochemical hazard rating. The KPs that intersect the various geologic units identified as part of this assessment are considered approximate as the scales used for geological mapping are typically much larger than that of the alignment. In addition, the desktop rating assumes all aspects of the unit-specific lithologic descriptions apply equally to their respective intersection segments of the ABC Section.

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6.0 FUTURE WORK In general, a more detailed, site-specific analysis is expected to follow field review and field-checking of the desktop assessment and terrain mapping. The priority would be to focus most attention on the high-rated hazards from this assessment. Specific recommendations vary with hazard type, as outlined in the following sections.

6.1. Landslide Hazards A general field review is recommended to check the desktop assessment and determine whether the inventory is complete. Further field-based assessment and field mapping of high and moderate-rated sites would be required in order to evaluate the need for mitigation and to initiate design where required. Subsequent analytical work and design would be informed by the findings of the field work. We do not currently anticipate that subsurface investigation will be needed to evaluate landslide hazards, but the field mapping may indicate otherwise.

6.2. Hydrotechnical Hazards Based on TCPL standard designs, all sites will require a scour analysis, and select sites require an evaluation of lateral channel stability. A field inspection program will be developed as part of the next scope of work. Following detailed analysis and ground-truthing of the preliminary inventory, BGC will provide an updated hydrotechnical hazard sites inventory which may result in some hazard sites being removed from the inventory (non-credible), or the addition of new sites. The updated inventory will also include a recommended min. DoC, and the KP stationing that min. DoC applies to, for each site.

6.3. Seismic Hazards Moderate-rated seismic liquefaction and landslide hazards will be recommended for site reconnaissance to check the desktop assessment and determine if follow-up site-specific investigations are warranted. High-rated liquefaction and landslide hazards will warrant ground reconnaissance to check assumed deposit types, soil textures and densities, local topography, and groundwater conditions. Site-specific investigations of liquefaction triggering and ground displacement potential may be recommended where loose, saturated deposits occur on topography that favours lateral spreads or flow slides. Similarly, site specific investigations of landslide triggering may be recommended where the field reconnaissance confirms the desktop-interpreted hazard. These investigations might include subsurface geotechnical investigations and numerical modelling. Suspected Quaternary fault crossings have not been identified; thus, no further work is expected.

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6.4. Subsidence Hazards The key next step for the subsidence hazards is a careful field review for subtle evidence of subsidence where the potential has been identified in this assessment. A shallow geophysical investigation may be required to fully delineate any voids or zones susceptible to subsidence.

6.5. Geotechnical Hazards Field review of the potential geotechnical hazard sites would support the development of a mitigation toolbox for hazards that are encountered during construction. This allows the project to recognize and manage previously unrecognized hazards sites efficiently.

6.6. Geochemical Hazards Field investigations will focus sampling near those areas where mineral occurrences have been identified through this desktop geochemical hazard assessment. Field efforts will be focused near segments where the ditch-line is anticipated to encounter shallow bedrock, where site-specific handling and management of excavated materials may be required as part of construction. Sample collection and testing will target the units’ dominant mineral composition, acid potential and neutralizing potential, metal abundance and water-soluble (short-term) leaching rates.

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REFERENCES

AMEC. (2014). Assessment of Metal Leaching and Acid Rock Drainage Potential of the East coast Connector Gas Transmission Project. Prepared for: Spectra Energy Transmission Inc. Prepared by AMEC Environmental and Infrastructure. 45p. Alberta Dam Safety (2020, April 30). Alberta Dam Safety Map. Online: http://damsafetymap.alberta.ca/ Alberta Geological Survey. (n.d.). Earthquakes in Alberta [Web site]. Retrieved from https://ags.aer.ca/activities/earthquakes-in-alberta.html Ashford, S.A., & Sitar, N. (2002). Simplified method for evaluating seismic stability of steep slopes. Journal of Geotechnical and Geoenvironmental Engineering, 128(2): 119-128. https://doi.org/10.1061/(ASCE)1090-0241(2002)128:2(119) Baranova, V., Mustaqeem, A., & Bell, S. (1999). A model for induced seismicity caused by hydrocarbon production in the Western Canada Sedimentary Basin. Canadian Journal of Earth Sciences, 36, 47-64. https://doi.org/10.1139/e98-080 BC Hydro. (2012, November). Dam Safety - Probabilistic Seismic Hazard Analysis (PSHA) Model (Engineering Report No. E658). BC Ministry of Energy and Mines (BCMEM). (1998). Policy for Metal Leaching and Acid Rock Drainage at Mine-sites in British Columbia. Issued by: Ministry of Energy and Mines and Ministry of Environment, Lands and Parks, July 1998. Bobrowski, P.T., & Rutter, N. M. (1992). The Quaternary geologic history of the Canadian Rocky Mountains. Geographie Physique et Quaternaire, 46(1), 5-15. https://doi.org/10.7202/032887ar Bray, J.D., & Macedo, J. (2019). Procedure for estimating shear-induced seismic slope displacement for shallow crustal earthquakes. Journal of Geotechnical and Geoenvironmental Engineering, 145(12), 04019106. https://doi.org/10.1061/(ASCE)GT.1943-5606.0002143 Building Seismic Safety Council. (1994). NEHRP recommended provisions for seismic regulations for new buildings, Part 1: Provisions. Retrieved from https://www.nibs.org/page/bssc_1994pubs Climatedata.ca (2020, April 30). Climate Data for a Resilient Canada – Crowsnest, AB. Version 1.8. online: https://climatedata.ca/explore/location/?loc=IAQRM&location-select- temperature=tx_max&location-select-precipitation=rx1day&location-select-other=frost_days Cruden, D.M. and Krahn, J. (1973). A reexamination of the geology of the Frank Slide. Canadian Geotechnical Journal, 10(4), pp.581-591. DataBC. (2020, April 30). B.C. Dams. online: https://catalogue.data.gov.bc.ca/dataset/bd632217-35f9-4d01-8e57-a6dbc454f236 DeMarchi, D.A. (2011). Ecoregions of British Columbia, Third Edition

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Ford, D.C. (1979). A review of alpine karst in the southern Rocky Mountains of Canada: National Speleological Society Bulletin, v. 41, p. 53-65. Geertsema, M., Schwab, J., Jordan, P., Millard, T., and Rollerson, T. (2010). Hillslope processes. In: Pike, R., Redding, T., Moore, R., Winker, R., and Bladon, K. (Eds.) 2010. Compendium of forest hydrology and geomorphology in British Columbia. British Columbia Ministry of Forestry, Forest Science Program, Victoria B.C., and FORREX Forum for Research and Extension in Natural Resources, Kamloops, B.C., Land Management Handbook 66. Halchuk, S.C., Adams, J.E., & Allen, T.I. (2015a). Fifth generation seismic hazard model for Canada: grid values of mean hazard to be used with the 2015 National Building Code of Canada (GSC Open File 7893). https://doi.org/10.4095/297378 Halchuk, S., Allen, T.I., Rogers, G.C., & Adams, J. (2015b). Seismic hazard earthquake epicentre file (SHEEF2010) used in the fifth generation seismic hazard maps of Canada (GSC Open File 7724). https://doi.org/10.4095/296908 Howes, D.E., and Kenk, E. (eds.). (1997). Terrain Classification System for British Columbia, Version 2. A system for the classification of surficial materials, landforms and geological processes of British Columbia. Resource Inventory Branch, Ministry of Environment, Lands and Parks, Province of B.C. Victoria, B.C. 100 pp. International Network of Acid Prevention (INAP). (2012). The Global Acid Rock Drainage (GARD) Guide. International Network for Acid Prevention. http://www.gardguide.com/index.php?title=Main_Page McConnell, R.G., and Brock, R.W. (1904). Report on the great landslide at Frank, Alberta, Canada. Canadian Department of Interior, Annual Report, 1902–1903, Part 8. MESH. (2006). Acid Rock Drainage and Metal Leaching Assessment for the Proposed Kitimat- Summit Lake Natural Gas Pipeline Looping Project. Prepared for Pacific Trail Pipelines. Prepared by: MESH Environmental Inc. 42p. Mine Environmental Neutral Drainage (MEND). (2009). Prediction Manual for Drainage Chemistry from Sulphidic Geologic Materials. Mine Environment Neutral Drainage. MEND Report 1.20.1, December, 2009. Monger, J.W.H., & Price, R.A. (1978). Geodynamic evolution of the Canadian Cordillera – progress and problems. Canadian Journal of Earth Sciences, 16, 770-791. https://doi.org/10.1139/e79-069 Monger, J., & Price, R. (2002). The Canadian Cordillera: geology and tectonic evolution. CSEG Recorder, 27(2), 17-35. Mueller, C.S. (2018). Earthquake catalogs compiled for the USGS National Seismic Hazard Models [Data]. US Geological Survey data release, retrieved from https://doi.org/10.5066/F7P26X4R

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Natural Regions Committee. (2006). Natural Regions and Subregions of Alberta. Compiled by D.J. Downing and W.W. Pettapiece. Government of Alberta. Pub. No. T/852. https://open.alberta.ca/dataset/dd01aa27-2c64-46ca-bc93- ca7ab5a145a4/resource/98f6a93e-c629-46fc-a025-114d79a0250d/download/2006- nrsrcomplete-may.pdf National Research Council of Canada. (2015). National building code of Canada 2015. Ottawa, ON: NRCC Natural Resources Canada (NRCAN). (2020). Search the earthquake database [Web page]. Retrieved from https://earthquakescanada.nrcan.gc.ca/stndon/NEDB-BNDS/bulletin-en.php Price, R.A. (2013). Geology, Fernie, British Columbia-Alberta [Map]. Scale 1:125,000. GSC Map 2200A. https:/doi.org/10.4095/292659 Quinn, P., Zaleski, M., Mayfield, R., Karimian, H., and Waddington, B. (2015, September). Liquefaction susceptibility mapping derived from terrain mapping; experience on a linear project in British Columbia, Canada. GEOQuébec 2015. Paper presented at the 68th Canadian Geotechnical Conference and the 7th Canadian Permafrost Conference, Québec, QC. Rathje, E.M., & Bray, J.D. (2001). One- and two-dimensional seismic analysis of solid-waste landfills. Canadian Geotechnical Journal, 38(4), 850-862. https://doi.org/10.1139/t01-009 Resources Inventory Committee (1996). Guidelines and standards for terrain mapping in British Columbia. Government of British Columbia, Victoria Schultz, R., Stern, V., & Gu, Y.J. (2014). An investigation of seismicity clustered near the Cordel Field, west central Alberta, and its relation to a nearby disposal well. Journal of Geophysical Research: Solid Earth, 119, 3410-3423. https://doi.org/10.1002/2013JB010836 Stern, V.H., Schultz, R.J., Shen, L., Gu, Y.J., & Eaton, D.W. (2018, April 3). Alberta earthquake catalogue, version 6.0 [GIS data]. Retrieved from https://ags.aer.ca/publications/ DIG_2013_0017.html Stockmal, G.S. and Fallas, K.M. (comp.). (2015). Geology, Chinook South, Alberta–British Columbia [Map and GIS data]. Scale 1:100,000. GSC Open File 7476. https://doi.org/10.4095/297169 Stokes, T., Griffiths, P., and Ramsey, C. (2010). Karst geomorphology, hydrology, and management. In: Pike, R., Redding, T., Moore, R., Winker, R., and Bladon, K. (Eds.) 2010. Compendium of forest hydrology and geomorphology in British Columbia. British Columbia Ministry of Forestry, Forest Science Program, Victoria B.C., and FORREX Forum for Research and Extension in Natural Resources, Kamloops, B.C., Land Management Handbook 66.

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TransMountain Pipeline Expansion Project (TMEP). (2015). Acid Rock Drainage and Metal Leaching Potential. Prepared for: Trans Mountain Pipeline ULC, Trans Mountain Expansion Project. Prepared by: BGC Engineering. 179p. U.S. Geological Survey. (n.d.). Search earthquake catalog [Web page]. Retrieved from https://earthquake.usgs.gov/earthquakes/search/ U.S. Geological Survey and Montana Bureau of Mines and Geology. (n.d.). Quaternary fault and fold database for the United States [Web page]. Retrieved from https://www.usgs.gov/natural- hazards/earthquake-hazards/faults. Wetmiller, R.J. (1986). Earthquakes near Rocky Mountain House, Alberta, and their relationship to gas production facilities. Canadian Journal of Earth Sciences, 23, 172-181. https://doi.org/10.1139/e86-020 Wieczoriek, G.F., Wilson, R.C., & Harp. E.L. (1985). Map showing slope stability during earthquakes in San Mateo County, California [Map]. Scale 1:62,500. USGS Miscellaneous Investigations Series Map I-1257-E. Retrieved from https://pubs.usgs.gov/imap/1257e/plate- 1.pdf Wilson, R.C., & Keefer, D.K. (1985). Predicting areal limits of earthquake-induced landsliding. In J. Ziony (Ed.), Evaluating Earthquake Hazards in the Los Angeles Region – An Earth Science Perspective (USGS Professional Paper 1360, pp. 316-345). https://doi.org/10.3133/pp1360

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DRAWINGS

June 2020 Page 96 of 132 NOVA Gas Transmission Ltd. Attachment 6

NGTL West Path Delivery 2022 668,000 670,000 672,000 674,000 Desktop1600 Geohazards676,000 Preliminary Assessment INSET VIEW OF THE SOUTHEAST CORNER OF BRITISH COLUMBIA (CROWSNEST AREA) 1900 ! Kimberley ! HY22 HY95A Hosmer Lundbreck ! ! HY3 ALBERTA Cranbrook Fernie ! ! ABC HY93 1500 SECTION 2100 ³ 5,504,000 1600 5,504,000 1700

1800 1900 BRITISH 2000

2200 HY95 2300 2400 COLUMBIA 2400 ! Moyie 2400

1500

KOOTENAY HW93 HY3 LAKE HY95 ! Grasmere ! PHILLIPPS PEAK ! Yahk Roosville Kingsgate ! ! 1500

5,502,000 5,502,000

! ALBERTA 4+000 4+500 ! 3+500 !

BRITISH COLUMBIA 5+000 ! ! ! 3+000 5+211 ! PHILLIPPS 1400 2+500 2+000 LAKE ! 1+500 !

1+000 ! 0+500 ! 1800 1500 CROWSNEST ! 0+000 LAKE 1700

1600

SENTINEL

CROWSNEST RIVER 5,500,000 LEGEND 5,500,000 ! KILOMETRE POST EMERALD LAKE 1400 PROPOSED PIPELINE SECTIONS 1400 SCALE 1:25,000 TC WESTERN SYSTEM 250 0 250 500 750 1500 STREAM 1400 1600 METRES ROAD 1700 THIS DRAWING1500 MAY HAVE BEEN REDUCED OR ENLARGED. CROWSNEST HWY 3 ALL FRACTIONAL SCALE NOTATIONS INDICATED ARE 1800 BASED ON ORIGINAL FORMAT DRAWINGS.

668,000 670,000 672,000 674,000 WATERBODY676,000 1600 SCALE: PROJECT: NOTES: 1:25,000 WESTERN ALBERTA SYSTEM MAINLINE LOOP 2 1. ALL DIMENSIONS ARE IN METRES UNLESS OTHERWISE NOTED. 7. UNLESS BGC AGREES OTHERWISE IN WRITING, THIS DRAWING SHALL NOT BE MODIFIED OR USED FOR ANY PURPOSE ALBERTA BRITISH COLUMBIA SECTION - 2. THIS DRAWING MUST BE READ IN CONJUNCTION WITH BGC'S REPORT TITLED "NOVA GAS TRANSMISSION LTD. - OTHER THAN THE PURPOSE FOR WHICH BGC GENERATED IT. BGC SHALL HAVE NO LIABILITY FOR ANY DAMAGES OR LOSS DATE: MAY 2020 WESTERN ALBERTA SYSTEM MAINLINE LOOP 2 ALBERTA BRITISH COLUMBIA SECTION - DESKTOP BGC ENGINEERING INC. DESKTOP GEOHAZARDS PRELIMINARY ASSESSMENT ARISING IN ANY WAY FROM ANY USE OR MODIFICATION OF THIS DOCUMENT NOT AUTHORIZED BY BGC. ANY USE OF OR AN APPLIED EARTH SCIENCES COMPANY GEOHAZARDS PRELIMINARY ASSESSMENT", AND DATED MAY 2020. DRAWN: B G C TITLE: RELIANCE UPON THIS DOCUMENT OR ITS CONTENT BY THIRD PARTIES SHALL BE AT SUCH THIRD PARTIES' SOLE RISK. STT 3. HILLSHADE BASED ON LIDAR PROVIDED BY AIRBORNE IMAGING DATED JULY 2010 AND GEOBASE CDED DEM CLIENT: LOOP SECTION OVERVIEW DATED 2018. CONTOUR INTERVAL IS 25 m. CHECKED: 4. ALBERTA BRITISH COLUMBIA SECTION ALIGNMENT REV 2 PROVIDED BY TC ENERGY ON APRIL 9, 2020. LGT PROJECT No.: DWG No: 5. WATERCOURSE AND WATERBODY DATA FROM GEOBASE NATIONAL HYDRO NETWORK. 6. HORIZONTAL PROJECTION IS NAD 1983 UTM ZONE 11. VERTICAL DATUM IS UNKNOWN. APPROVED: 0098187 01 DG NOVA GAS TRANSMISSION LTD. (NGTL)

JuneX:\Projects\0098\187\GIS\Production\20200427_WASML_Loop2_Alberta_Section\ABC\01_Loop_Section_Overview.mxd 2020 Page 97 of 132 NOVA Gas Transmission Ltd. Attachment 6

NGTL West Path Delivery 2022 668,000 670,000 672,000 674,000 Desktop1600 Geohazards676,000 Preliminary Assessment INSET VIEW OF THE SOUTHEAST CORNER OF BRITISH COLUMBIA

2300 (CROWSNEST AREA) R C Sparwood ! Kimberley ! HY22 HY95A FG Hosmer Lundbreck 2300 ! ! HY3 ALBERTA Cranbrook Fernie ! ! ABC 1500 HY93 SECTION ³ 5,504,000 5,504,000 BRITISH 2200 HY95 2400 2400 2400 ! COLUMBIA Moyie M

KOOTENAY HW93 HY3 LAKE HY95 ! Grasmere ! PHILLIPPS PEAK R ! Yahk Roosville Kingsgate ! !

2100

2000

1900 C

1700 1800

5,502,000 5,502,000 1600 ! ALBERTA 4+000 4+500 ! 3+500 ! BRITISH COLUMBIA 5+000 ! ! 5+211 ! 3+000 F ! PHILLIPPS 2+500

1500 2+000 LAKE !

1700 1+500 FG !

1400 1+000 1500 ! 0+500 1800 CROWSNEST ! ! LAKE 0+000 LEGEND

1600 ! KILOMETRE POST C PROPOSED PIPELINE SECTIONS TC WESTERN SYSTEM SENTINEL FG F STREAM 1400 CROWSNEST RIVER ROAD

5,500,000 1400 CROWSNEST HWY 3 5,500,000 M EMERALD WATERBODY ISLAND LAKE LAKE SURFICIAL GEOLOGY SCALE 1:25,000 F FG FLUVIAL DEPOSITS (F) 250 0 250 500 750 1500 COLLUVIAL DEPOSITS (C) 1600 M METRES R GLACIOFLUVIAL DEPOSITS (FG) 1500 1700 THIS DRAWING MAY HAVE BEEN REDUCED OR ENLARGED. MORAINE (M) ALL FRACTIONAL SCALE NOTATIONS INDICATED ARE BASED ON ORIGINAL FORMAT DRAWINGS. 1800

668,000 670,000 672,000 674,000 BEDROCK (R)676,000 1600 SCALE: PROJECT: NOTES: 1:25,000 WESTERN ALBERTA SYSTEM MAINLINE LOOP 2 7. UNLESS BGC AGREES OTHERWISE IN WRITING, THIS DRAWING SHALL NOT BE MODIFIED OR USED FOR ANY PURPOSE 1. ALL DIMENSIONS ARE IN METRES UNLESS OTHERWISE NOTED. ALBERTA BRITISH COLUMBIA SECTION - 2. THIS DRAWING MUST BE READ IN CONJUNCTION WITH BGC'S REPORT TITLED "NOVA GAS TRANSMISSION LTD. - OTHER THAN THE PURPOSE FOR WHICH BGC GENERATED IT. BGC SHALL HAVE NO LIABILITY FOR ANY DAMAGES OR LOSS DATE: MAY 2020 BGC ENGINEERING INC. WESTERN ALBERTA SYSTEM MAINLINE LOOP 2 ALBERTA BRITISH COLUMBIA SECTION - DESKTOP DESKTOP GEOHAZARDS PRELIMINARY ASSESSMENT ARISING IN ANY WAY FROM ANY USE OR MODIFICATION OF THIS DOCUMENT NOT AUTHORIZED BY BGC. ANY USE OF OR AN APPLIED EARTH SCIENCES COMPANY GEOHAZARDS PRELIMINARY ASSESSMENT", AND DATED MAY 2020. DRAWN: B G C TITLE: RELIANCE UPON THIS DOCUMENT OR ITS CONTENT BY THIRD PARTIES SHALL BE AT SUCH THIRD PARTIES' SOLE RISK. STT 3. HILLSHADE BASED ON LIDAR PROVIDED BY AIRBORNE IMAGING DATED JULY 2010 AND GEOBASE CDED DEM CLIENT: SURFICIAL GEOLOGY DATED 2018. CONTOUR INTERVAL IS 25 m. CHECKED: 4. SURFICIAL GEOLOGY DATA FROM FENTON ET AL, AGS MAP 601, 1:1000000. LGT PROJECT No.: DWG No: 5. ALBERTA BRITISH COLUMBIA SECTION ALIGNMENT REV 2 PROVIDED BY TC ENERGY ON APRIL 9, 2020. 6. HORIZONTAL PROJECTION IS NAD 1983 UTM ZONE 11. VERTICAL DATUM IS UNKNOWN. APPROVED: 0098187 02 DG NOVA GAS TRANSMISSION LTD. (NGTL)

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668,000 670,000 672,000 674,000 676,000 NGTL West Path Delivery 2022 .. .. Desktop1600 Geohazards Preliminary Assessment INSET VIEW OF THE SOUTHEAST CORNER OF BRITISH COLUMBIA

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(( 7. HORIZONTAL PROJECTION IS NAD 1983 UTM ZONE 11. VERTICAL DATUM IS UNKNOWN. .. ALBERTA BRITISH COLUMBIA SECTION - 2. THIS DRAWING MUST BE READ IN CONJUNCTION WITH BGC'S REPORT TITLED "NOVA GAS TRANSMISSION LTD. - 8. UNLESS BGC AGREES OTHERWISE IN WRITING, THIS DRAWING SHALL NOT BE MODIFIED OR USED FOR ANY PURPOSE DATE: MAY 2020 WESTERN ALBERTA SYSTEM MAINLINE LOOP 2 ALBERTA BRITISH COLUMBIA SECTION - DESKTOP BGC ENGINEERING INC. DESKTOP GEOHAZARDS PRELIMINARY ASSESSMENT ..

GEOHAZARDS PRELIMINARY ASSESSMENT", AND DATED MAY 2020. OTHER THAN THE PURPOSE FOR WHICH BGC GENERATED IT. BGC SHALL HAVE NO LIABILITY FOR ANY DAMAGES OR LOSS B G C AN APPLIED EARTH SCIENCES COMPANY (( DRAWN: TITLE: .. ARISING IN ANY WAY FROM ANY USE OR MODIFICATION OF THIS DOCUMENT NOT AUTHORIZED BY BGC. ANY USE OF OR 3. HILLSHADE BASED ON LIDAR PROVIDED BY AIRBORNE IMAGING DATED JULY 2010 AND GEOBASE CDED DEM STT BEDROCK GEOLOGY DATED 2018. CONTOUR INTERVAL IS 25 m. RELIANCE UPON THIS DOCUMENT OR ITS CONTENT BY THIRD PARTIES SHALL BE AT SUCH THIRD PARTIES' SOLE RISK. CLIENT: CHECKED:

4. BEDROCK GEOLOGY DATA FROM STOCKMAL AND FALLAS (2015). LGT (( PROJECT No.: DWG No:

5. ALBERTA BRITISH COLUMBIA SECTION ALIGNMENT REV 2 PROVIDED BY TC ENERGY ON APRIL 9, 2020. ..

6. WATERCOURSE AND WATERBODY DATA FROM GEOBASE NATIONAL HYDRO NETWORK. APPROVED: MZ 0098187 03

.. .. NOVA GAS TRANSMISSION LTD. (NGTL)

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..

..

.. ..

..

.. ..

..

..

..

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.. ..

..

..

.. ..

..

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...... NOVA Gas Transmission Ltd. Attachment 6

NGTL West Path Delivery 2022 668,000 670,000 672,000 674,000 Desktop1600 Geohazards676,000 Preliminary Assessment INSET VIEW OF THE SOUTHEAST CORNER OF BRITISH COLUMBIA

2300 (CROWSNEST AREA) Sparwood ! Kimberley ! HY22 HY95A Hosmer Lundbreck 2300 ! ! HY3 ALBERTA Cranbrook Fernie ! ! ABC 1500 HY93 SECTION ³ 5,504,000 2400 5,504,000

2200 HY95 BRITISH COLUMBIA 2400 ! Moyie

KOOTENAY HW93 Rs//Cv-R^b HY3 LAKE HY95 ! Grasmere ! PHILLIPPS PEAK ! Yahk Roosville Kingsgate ! rCk-Rb !

2100

1600

Rs/Cv-R^bR^d

2000

Rsk//Cv 1800 1900

Rsk.Cv-VRd Cv/Rsk-R^s 1700 Cb Rsk.Cv Cb-Rd Rar/Cv Rs/Cv Cv/Rks

5,502,000 Rs/Cv Rks/Cv Cw 5,502,000 Ffp Mv[Ru] Cb Cv.Rk ! ALBERTA Cf-Rd 4+500 lake ! Mw[Ru] Mu-E Mv//Rar 4+000 !3+500 Rrk/Cv BRITISH COLUMBIA Cb ! Rks/Cv !3+000 Cv.Rk 5+000 Cv.Rks !5+211 Mw[Ru] !2+500 Cb Cbu

1500 FGf !2+000 FGt 1700 Cv//Ra Mw[Ru] Rks/Cv Ov[FGu] !1+500 FGp Cv/Rau 1400 1500 LEGEND !1+000 FGtu FGu Ov[FGu] ! KILOMETRE POST rCv/Rks CROWSNEST !0+500 !0+000 1800 LAKE PROPOSED PIPELINE SECTIONS FGp 1600 TC WESTERN SYSTEM STREAM ROAD SENTINEL CROWSNEST HWY 3 1400 CROWSNEST RIVER WATERBODY

5,500,000 1400 TERRAIN MAPPING POLYGONS 5,500,000

EMERALD LAKE ISLAND LAKE LAKE ORGANIC SCALE 1:25,000 FLUVIAL 250 0 250 500 750 1500 COLLUVIUM METRES 1600 GLACIOFLUVIAL 1500 1700 THIS DRAWING MAY HAVE BEEN REDUCED OR ENLARGED. TILL ALL FRACTIONAL SCALE NOTATIONS INDICATED ARE BASED ON ORIGINAL FORMAT DRAWINGS. 1800

668,000 670,000 672,000 674,000 ROCK 676,000 1600 SCALE: PROJECT: NOTES: 1:25,000 WESTERN ALBERTA SYSTEM MAINLINE LOOP 2 1. ALL DIMENSIONS ARE IN METRES UNLESS OTHERWISE NOTED. 7. UNLESS BGC AGREES OTHERWISE IN WRITING, THIS DRAWING SHALL NOT BE MODIFIED OR USED FOR ANY PURPOSE ALBERTA BRITISH COLUMBIA SECTION - 2. THIS DRAWING MUST BE READ IN CONJUNCTION WITH BGC'S REPORT TITLED "NOVA GAS TRANSMISSION LTD. - OTHER THAN THE PURPOSE FOR WHICH BGC GENERATED IT. BGC SHALL HAVE NO LIABILITY FOR ANY DAMAGES OR LOSS DATE: MAY 2020 BGC ENGINEERING INC. WESTERN ALBERTA SYSTEM MAINLINE LOOP 2 ALBERTA BRITISH COLUMBIA SECTION - DESKTOP ARISING IN ANY WAY FROM ANY USE OR MODIFICATION OF THIS DOCUMENT NOT AUTHORIZED BY BGC. ANY USE OF OR DESKTOP GEOHAZARDS PRELIMINARY ASSESSMENT AN APPLIED EARTH SCIENCES COMPANY GEOHAZARDS PRELIMINARY ASSESSMENT", AND DATED MAY 2020. RELIANCE UPON THIS DOCUMENT OR ITS CONTENT BY THIRD PARTIES SHALL BE AT SUCH THIRD PARTIES' SOLE RISK. DRAWN: B G C TITLE: 3. HILLSHADE BASED ON LIDAR PROVIDED BY AIRBORNE IMAGING DATED JULY 2010 AND GEOBASE CDED DEM STT TERRAIN MAPPING DATED 2018. CONTOUR INTERVAL IS 25 m. CLIENT: CHECKED: 4. ALBERTA BRITISH COLUMBIA SECTION ALIGNMENT REV 2 PROVIDED BY TC ENERGY ON APRIL 9, 2020. LGT PROJECT No.: DWG No: 5. WATERCOURSE AND WATERBODY DATA FROM GEOBASE NATIONAL HYDRO NETWORK. 6. HORIZONTAL PROJECTION IS NAD 1983 UTM ZONE 11. VERTICAL DATUM IS UNKNOWN. APPROVED: 0098187 04A BW NOVA GAS TRANSMISSION LTD. (NGTL)

JuneX:\Projects\0098\187\GIS\Production\20200427_WASML_Loop2_Alberta_Section\ABC\04A_Terrain_Mapping.mxd 2020 Page 100 of 132 NOVA Gas Transmission Ltd. Attachment 6 NGTL West Path Delivery 2022 Desktop Geohazards Preliminary Assessment Terrain Mapping Legend

SimpleTerrain Symbols: U s e dwhe none surficial material pres is e ntwithin apolygon Examples

Example: Cb–R b R s–V //Cv R ”b w Stee pbe d rockslope with <20% cove of ra colluvial ve ne e r; gulliedwith initiationzone sfor rockfall. We lldraine d SurficialMaterial Geomorphological proce s ssub-type Fapi Activeflood plain.Impe rfectlydraine d Surface expres s ion Geomorphological Surface expres proce s ion s s(up tomay 3 be as s igne d ) Mw[R m]w-m mantleTill ofvariable thickne s sove rlyingrolling be d rock.We lltomod e ratelywe lldraine d Ck–R w b Colluvialslope subject torockfall (talus slope we ) lldraine d ComposTerrain ite Symbols: U s e dwhe orterrain n2 3 type sare pres e ntwithin apolygon TexturalTerms and Symbols Cv.Mv ind icatesthat ‘C’ and ‘M’ are roughly equal extentin Cv/Mv ind icatesthat greater‘C’ is extentin than ‘M’ (about 60:40) a blocks c clay Cv//Mv ind icatesthat much‘C’ is greater extentin than ‘M’ (about 80:20) b boulde rs x angularfragme nts k cobbles g grave l StratigraphicTerrain Symbols p pe bbles m mud s s and d mixedfragme nts Cv[Mj] ind icatesthat ‘Cv’ ove rlies‘Mj’Note:also is ][ us e dinstead ofa ve rticallineon some maps z s ilt

SurficialMaterial Type s SoilDrainage Clas s e s A AnthropogenicLG Glaciolacus trine C Colluvium M GlacialTill r R apidlydraine d W aterremove is dfrom the soilrapidly relationin tosupply. F Fluvial N Notmappe d(us uallyalake or large rive r) w W e ll-draine d W aterremove is dfrom the soilread but ily not rapidly. FG Glaciofluvial O O rganic Mod e ratelywe ll-draine d W aterremove is dfrom the soilsome whatslowly relationin tosupply. L Lacus trine R Bed rock m W aterremove is dfrom the soilsufficiently slowly relationin tosupply toke e p i Impe rfectlydraine d SurfaceExpres s ions thesoilwe for t asignificant part ofthe growing se as on. W aterremove is dso slowly relationin tosupply that the soilremains we for t a P oorlydraine d p comparative lylarge part ofthe time the notsoil is froze n. a Mod e rateSlope (15-26°) p P lain(0-3°) W aterremove is dfrom the soilso slowly that the water table remains ator on Blankemthick (>2 t de pos it) R idge V e rypoorly draine d b r v thesurface for the greater part ofthe time the notsoil is froze n. c Cone(>15°) s Stee pSlope (>35°) f Fan(<15°) t Terrace TerrainStability Clas s h H ummocky u U nd ulating j GentleSlope (4-14°) v V e nemthick e (0-2 rde pos it) I P olygonstable, is and no significant slope instability or eros ionproblems are pres e nt. k Mod e ratelyStee pSlope (27-35°) w V ariableThickne s sDepos it) II P olygonstable, is and the reave is rylow like lihoodof slope instability or eros in ioninitiating m R olling thepolygon following cut and construction.fill Minor slumping expe is ctedalong soil cuts, e s pe ciallyforor years1 2 following construction. ActivityLeve l P olygonstable, is and the rea lowis to mod e ratelike lihoodof slope instability or eros ion FAp ‘AInd’ icatesactive flood plain(subject tochanne changes l ) III CIf ‘I’ Ind icatesinactive fan the in initiating polygon following cut and construction.fill Minor slumping expe is ctedalong scuts, oil es pe ciallyforor years1 2 following construction. GeomorphologicProce s s e s IV P olygonmarginally is stable, and expe is it ctedto contain areas with a mod e rateto high R R apidland s lide(runout zone ) E Me ltwater channe ls K Karst like lihoodof slope instability or eros ioninitiatingthe in polygon following cut and fill R ^ R apidland s lidezone(initiation ) F^ Slowland s lidezone(initiation ) U d Debris construction.W e tse as onconstruction will furthe rincreas ethe like lihoodof construction- Flood relatedslope instability or eros ion. H Kettled V Gullyeros ion V P olygonunstable, is and expe is ctedto contain areas with ahighlike lihoodof slope instability GeomorphologicalProce s sSubtype s oreros the in ioninitiating polygon following cut and construction.fill We se t as onconstruction willfurthe increas r ethe like lihoodofconstruction-related instability or eros ion. b R ockfall s Debrisavalanche s d Debrisflows u Surficialmaterial slump

SCALE: P R O J ECT: NO TES: NTS W ESTERALBERTA N SYSTEM MAINLINE LO O P2 1. THISDR 1. AW INGMU STBEREAD COIN NJU NCTIONWITH BGC'S REPO RTITLED T "NO VGAS A TRANSMISSION WESTER - LTD. ALBERTA N SYSTEM MAINLINE LO OALBER P2 BR TA CO ITISH LUMBIASECTION - DATE: ALBERTABR CO ITISH LUMBIASECTION - DESKTO PGEO H AZAR DSPR ELIMINARYASSESSMENT", AND DATED MAY 2020. MAY2020 BGCENGINEER INGINC. DESKTO PGEO H AZAR DSPR ELIMINARYASSESSMENT 2. UNLESS 2. BGC AGR EESOTH ERWWRIN ISE THISDR ITING, AW INGSH ALLNO BEMO T DIFIEDOR USED FO RANY PU R P O SEOTH ERTHAN THE PU R P O SEFO RWH ICHBGC GENER BGC ATEDSHIT. ALL ANAPP LIEDEARTH SCIENCES CO MP ANY DR AW N: TITLE: HAVE NO LIABILITYFO RANY DAMAGES OR LO SSARISING ANYIN WAY FRO MANY USE OR MO DIFICATIONOF THISDO CU MENTNO AU T THO R IZEDBY BGC.ANY USE OF OR RELIANCE UP O NTHIS STT B GC TER RMAP AIN LEGEND CLIENT: DO CU MENTOR COITS NTENTBY THIRD PAR SH TIES ALLBESUAT CHTHIRD PAR SO TIES' LERISK. CH ECKED: LGT P R O J ECTNo.: DW GNo.: APP R O V ED: 0098187 04B BW NO VGAS A TRANSMISSION (NGTL)LTD.

\ oet\0817GSPrduto\0047WAM_op_leraScinAC0BTranLgn .mxd rta_Section\ABC\04B_Terrain_Legend ASML_Loop2_Albe uction\20200427_W rod June rojects\0098\187\GIS\P X :\P 2020 Page 101 of 132 NOVA Gas Transmission Ltd. Attachment 6

NGTL West Path Delivery 2022 668,000 670,000 672,000 674,000 Desktop1600 Geohazards676,000 Preliminary Assessment INSET VIEW OF THE SOUTHEAST CORNER OF BRITISH COLUMBIA (CROWSNEST AREA) 1900

Kimberley ! HY22 HY95A ALBERTA HY3 Cranbrook Fernie ! ! ABC HY93 SECTION 1500 2100 ³ 5,504,000 1600 5,504,000 1700

1800 1900 BRITISH 2000

2200 HY95 2300 2400 COLUMBIA 2400 2400

1500 HW93 HY3 KOOTENAY HY95 LAKE ! PHILLIPPS PEAK

1500

5,502,000 5,502,000 MORAINE DAM ! ALBERTA 4+000 (APPROXIMATE) 4+500 ! 3+500 !

BRITISH COLUMBIA 5+000 ! ! ! 3+000 5+211 ! PHILLIPPS 1400 2+500 2+000 LAKE ! 1+500 !

1+000 ! 0+500 ! 1800 1500 CROWSNEST ! 0+000 LAKE 1700

1600 LEGEND

! KILOMETRE POST PROPOSED PIPELINE SENTINEL SECTIONS TC WESTERN SYSTEM CROWSNEST RIVER STREAM 5,500,000 5,500,000 ROAD EMERALD ISLAND LAKE LAKE CROWSNEST HWY 3 1400 1400 WATERBODY SCALE 1:25,000 250 0 250 500 750 1500 DESKTOP LANDSLIDE HAZARD 1400 RATING 1600 METRES 1700 MODERATE THIS DRAWING1500 MAY HAVE BEEN REDUCED OR ENLARGED. ALL FRACTIONAL SCALE NOTATIONS INDICATED ARE 1800 BASED ON ORIGINAL FORMAT DRAWINGS. LOW 1600 668,000 670,000 672,000 674,000 676,000 SCALE: PROJECT: NOTES: 1:25,000 WESTERN ALBERTA SYSTEM MAINLINE LOOP 2 1. ALL DIMENSIONS ARE IN METRES UNLESS OTHERWISE NOTED. 7. UNLESS BGC AGREES OTHERWISE IN WRITING, THIS DRAWING SHALL NOT BE MODIFIED OR USED FOR ANY PURPOSE ALBERTA BRITISH COLUMBIA SECTION - 2. THIS DRAWING MUST BE READ IN CONJUNCTION WITH BGC'S REPORT TITLED "NOVA GAS TRANSMISSION LTD. - OTHER THAN THE PURPOSE FOR WHICH BGC GENERATED IT. BGC SHALL HAVE NO LIABILITY FOR ANY DAMAGES OR LOSS DATE: MAY 2020 BGC ENGINEERING INC. WESTERN ALBERTA SYSTEM MAINLINE LOOP 2 ALBERTA BRITISH COLUMBIA SECTION - DESKTOP ARISING IN ANY WAY FROM ANY USE OR MODIFICATION OF THIS DOCUMENT NOT AUTHORIZED BY BGC. ANY USE OF OR DESKTOP GEOHAZARDS PRELIMINARY ASSESSMENT AN APPLIED EARTH SCIENCES COMPANY GEOHAZARDS PRELIMINARY ASSESSMENT", AND DATED MAY 2020. RELIANCE UPON THIS DOCUMENT OR ITS CONTENT BY THIRD PARTIES SHALL BE AT SUCH THIRD PARTIES' SOLE RISK. DRAWN: B G C TITLE: 3. HILLSHADE BASED ON LIDAR PROVIDED BY AIRBORNE IMAGING DATED JULY 2010 AND GEOBASE CDED DEM STT LANDSLIDE HAZARDS DATED 2018. CONTOUR INTERVAL IS 25 m. CLIENT: CHECKED: 4. ALBERTA BRITISH COLUMBIA SECTION ALIGNMENT REV 2 PROVIDED BY TC ENERGY ON APRIL 9, 2020. LGT PROJECT No.: DWG No: 5. WATERCOURSE AND WATERBODY DATA FROM GEOBASE NATIONAL HYDRO NETWORK. 6. HORIZONTAL PROJECTION IS NAD 1983 UTM ZONE 11. VERTICAL DATUM IS UNKNOWN. APPROVED: 0098187 05 DG NOVA GAS TRANSMISSION LTD. (NGTL)

JuneX:\Projects\0098\187\GIS\Production\20200427_WASML_Loop2_Alberta_Section\ABC\05_Landslide_Hazards.mxd 2020 Page 102 of 132 NOVA Gas Transmission Ltd. Attachment 6

NGTL West Path Delivery 2022 668,000 670,000 672,000 !( 674,000 Desktop1600 Geohazards676,000 Preliminary Assessment INSET VIEW OF THE SOUTHEAST CORNER OF BRITISH COLUMBIA ALLISON CREEK (CROWSNEST AREA) 1900 HATCHERY MAIN DAM Kimberley ! HY22 HY95A ALBERTA HY3 Cranbrook Fernie ! ! ABC HY93 SECTION 1500 2100 ³ 5,504,000 1600 5,504,000 1700

1800 1900 BRITISH 2000

2200 HY95 2300 2400 COLUMBIA 2400 2400

1500 HW93 HY3 KOOTENAY HY95 LAKE ! PHILLIPPS PEAK

1500

5,502,000 GANSKE,H & 5,502,000 ! ALBERTA C-H-5 C-H-4 MIELKE,R DAM 4+500 ! !( !(! !( BRITISH COLUMBIA 4+000 3+500 C-H-6 ! ! C-H-3 (! 5+000 3+000 !( 5+211 ! 1400 PHILLIPPS 2+500 C-H-2 LAKE !( ! 2+000 1+500 !

1+000 ! C-H-1 ! 1800 1500 CROWSNEST !( ! LAKE 0+500 0+000 1700 LEGEND 1600 !( DAM ! KILOMETRE POST SENTINEL PROPOSED PIPELINE SECTIONS CROWSNEST RIVER TC WESTERN SYSTEM 5,500,000 5,500,000 STREAM EMERALD ROAD ISLAND LAKE LAKE 1400 1400 CROWSNEST HWY 3 SCALE 1:25,000 WATERBODY 250 0 250 500 750 1500 1400 DESKTOP HYDROTECHNICAL 1600 METRES HAZARD RATING 1700 THIS DRAWING1500 MAY HAVE BEEN REDUCED OR ENLARGED. !( MODERATE ALL FRACTIONAL SCALE NOTATIONS INDICATED ARE 1800 BASED ON ORIGINAL FORMAT DRAWINGS. LOW 668,000 670,000 672,000 674,000 !( 676,000 1600 SCALE: PROJECT: NOTES: 1:25,000 WESTERN ALBERTA SYSTEM MAINLINE LOOP 2 1. ALL DIMENSIONS ARE IN METRES UNLESS OTHERWISE NOTED. 7. UNLESS BGC AGREES OTHERWISE IN WRITING, THIS DRAWING SHALL NOT BE MODIFIED OR USED FOR ANY PURPOSE 2. THIS DRAWING MUST BE READ IN CONJUNCTION WITH BGC'S REPORT TITLED "NOVA GAS TRANSMISSION LTD. - DATE: ALBERTA BRITISH COLUMBIA SECTION - OTHER THAN THE PURPOSE FOR WHICH BGC GENERATED IT. BGC SHALL HAVE NO LIABILITY FOR ANY DAMAGES OR LOSS MAY 2020 BGC ENGINEERING INC. WESTERN ALBERTA SYSTEM MAINLINE LOOP 2 ALBERTA BRITISH COLUMBIA SECTION - DESKTOP ARISING IN ANY WAY FROM ANY USE OR MODIFICATION OF THIS DOCUMENT NOT AUTHORIZED BY BGC. ANY USE OF OR DESKTOP GEOHAZARDS PRELIMINARY ASSESSMENT AN APPLIED EARTH SCIENCES COMPANY GEOHAZARDS PRELIMINARY ASSESSMENT", AND DATED MAY 2020. RELIANCE UPON THIS DOCUMENT OR ITS CONTENT BY THIRD PARTIES SHALL BE AT SUCH THIRD PARTIES' SOLE RISK. DRAWN: B G C TITLE: 3. HILLSHADE BASED ON LIDAR PROVIDED BY AIRBORNE IMAGING DATED JULY 2010 AND GEOBASE CDED DEM STT HYDROTECHNICAL HAZARDS DATED 2018. CONTOUR INTERVAL IS 25 m. CLIENT: CHECKED: 4. ALBERTA BRITISH COLUMBIA SECTION ALIGNMENT REV 2 PROVIDED BY TC ENERGY ON APRIL 9, 2020. LGT PROJECT No.: DWG No: 5. WATERCOURSE AND WATERBODY DATA FROM GEOBASE NATIONAL HYDRO NETWORK. 6. HORIZONTAL PROJECTION IS NAD 1983 UTM ZONE 11. VERTICAL DATUM IS UNKNOWN. APPROVED: 0098187 06 RL NOVA GAS TRANSMISSION LTD. (NGTL)

JuneX:\Projects\0098\187\GIS\Production\20200427_WASML_Loop2_Alberta_Section\ABC\06_Hydrotechnical_Hazards.mxd 2020 Page 103 of 132 ..

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NOVA Gas Transmission Ltd. .. Attachment 6 ..

668,000 670,000 672,000 674,000 676,000 NGTL West Path Delivery 2022 .. .. Desktop1600 Geohazards Preliminary Assessment INSET VIEW OF THE SOUTHEAST CORNER OF BRITISH COLUMBIA

(CROWSNEST AREA) 1900

.. ..

.. ..

Kimberley .. ! HY22

HY95A

..

.. ALBERTA ..

Cranbrook HY3 .. .. Fernie .. ! ! ABC

HY93 SECTION .. 1500

2100 ³ ..

1600

5,504,000 .. 5,504,000 1700 .. 1800 1900 BRITISH .. 2000

2200 HY95 2300

(( 2400 COLUMBIA 2400 2400

(( .. .. 1500 .. ..

.. KOOTENAY HW93 HY3 (( HY95 LAKE ! PHILLIPPS PEAK

..

.. .. (( ..

..

.. 1500 (( ..

.. .. (( .. .. ((

((

((

.. ..

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(( .. ((

(( ((

..

..

......

((

((

((

.. ((

5,502,000 .. .. 5,502,000

.. .. !

ALBERTA (( (!(( 4+000 4+500 ! 3+500 (! (!!

BRITISH COLUMBIA

..

5+000 (( !

! .. (!.. (( ..

5+211 ! .. 3+000 (( !

PHILLIPPS 1400 (( 2+500 2+000

LAKE ! ((

.. ..

.. .. (( LEGEND 1+500 .. !

(( ! (( KILOMETRE POST

1+000

! .. FAULT, THRUST,

(( (( ...... 0+500 APPROXIMATE

.. !

1500 1800 CROWSNEST 0+000 (( (( (( ! LAKE FAULT, THRUST, INFERRED

1700 ..

(( .. (( 1600 (( PROPOSED PIPELINE SECTIONS

((

((

(( .. TC WESTERN SYSTEM ..

(( .. STREAM (( SENTINEL

ROAD (( .. CROWSNEST RIVER (( CROWSNEST HWY 3 5,500,000 5,500,000

(( WATERBODY

(( ..

(( EMERALD DESKTOP SEISMIC HAZARD ..

ISLAND LAKE .. (( LAKE (( 1400 RATING

1400 ((

SCALE 1:25,000 ..

.. HIGH ((

250 0 250 500 750 1500 (( ..

1400 .. MODERATE

(( 1600 METRES ((

1700 ..

.. LOW

THIS DRAWING1500 MAY HAVE BEEN REDUCED OR ENLARGED. (( ALL FRACTIONAL SCALE NOTATIONS INDICATED ARE 1800 .. BASED ON ORIGINAL FORMAT DRAWINGS. .. (! FAULT SEISMIC HAZARD

1600 668,000 670,000 672,000 674,000 676,000 ((

SCALE: PROJECT: NOTES: .. 1:25,000 WESTERN ALBERTA SYSTEM MAINLINE LOOP 2

1. ALL DIMENSIONS ARE IN METRES UNLESS OTHERWISE NOTED. 7. UNLESS BGC AGREES OTHERWISE IN WRITING, THIS DRAWING SHALL NOT BE MODIFIED OR USED FOR ANY PURPOSE

(( .. ALBERTA BRITISH COLUMBIA SECTION - 2. THIS DRAWING MUST BE READ IN CONJUNCTION WITH BGC'S REPORT TITLED "NOVA GAS TRANSMISSION LTD. - OTHER THAN THE PURPOSE FOR WHICH BGC GENERATED IT. BGC SHALL HAVE NO LIABILITY FOR ANY DAMAGES OR LOSS DATE: MAY 2020 WESTERN ALBERTA SYSTEM MAINLINE LOOP 2 ALBERTA BRITISH COLUMBIA SECTION - DESKTOP BGC ENGINEERING INC. DESKTOP GEOHAZARDS PRELIMINARY ASSESSMENT .. ARISING IN ANY WAY FROM ANY USE OR MODIFICATION OF THIS DOCUMENT NOT AUTHORIZED BY BGC. ANY USE OF OR

GEOHAZARDS PRELIMINARY ASSESSMENT", AND DATED MAY 2020. B G C AN APPLIED EARTH SCIENCES COMPANY

(( RELIANCE UPON THIS DOCUMENT OR ITS CONTENT BY THIRD PARTIES SHALL BE AT SUCH THIRD PARTIES' SOLE RISK. DRAWN: TITLE: 3. HILLSHADE BASED ON LIDAR PROVIDED BY AIRBORNE IMAGING DATED JULY 2010 AND GEOBASE CDED DEM .. STT SEISMIC HAZARDS DATED 2018. CONTOUR INTERVAL IS 25 m. CLIENT: CHECKED:

4. ALBERTA BRITISH COLUMBIA SECTION ALIGNMENT REV 2 PROVIDED BY TC ENERGY ON APRIL 9, 2020. LGT (( PROJECT No.: DWG No:

5. WATERCOURSE AND WATERBODY DATA FROM GEOBASE NATIONAL HYDRO NETWORK. ..

6. HORIZONTAL PROJECTION IS NAD 1983 UTM ZONE 11. VERTICAL DATUM IS UNKNOWN. APPROVED: MZ 0098187 07

.. .. NOVA GAS TRANSMISSION LTD. (NGTL)

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NGTL West Path Delivery 2022 668,000 670,000 672,000 674,000 Desktop1600 Geohazards676,000 Preliminary Assessment INSET VIEW OF THE SOUTHEAST CORNER OF BRITISH COLUMBIA (CROWSNEST AREA) 1900

Kimberley ! HY22 HY95A ALBERTA HY3 Cranbrook Fernie ! ! ABC HY93 SECTION 1500 2100 ³ 5,504,000 1600 5,504,000 1700

1800 1900 BRITISH 2000

2200 HY95 2300 2400 COLUMBIA 2400 2400

1500 HW93 HY3 KOOTENAY HY95 LAKE ! PHILLIPPS PEAK

1500

5,502,000 5,502,000

! ALBERTA 4+000 4+500 ! 3+500 !

BRITISH COLUMBIA 5+000 ! ! ! 3+000 5+211 ! PHILLIPPS 1400 2+500 2+000 LAKE ! 1+500 !

1+000 ! 0+500 ! 1800 1500 CROWSNEST ! 0+000 LAKE 1700

1600 LEGEND

! KILOMETRE POST SENTINEL PROPOSED PIPELINE SECTIONS CROWSNEST RIVER TC WESTERN SYSTEM 5,500,000 5,500,000 STREAM EMERALD ROAD ISLAND LAKE LAKE 1400 1400 CROWSNEST HWY 3 SCALE 1:25,000 WATERBODY 250 0 250 500 750 1500 1400 SUBSIDENCE HAZARD RATING 1600 METRES 1700 MODERATE THIS DRAWING1500 MAY HAVE BEEN REDUCED OR ENLARGED. ALL FRACTIONAL SCALE NOTATIONS INDICATED ARE 1800 BASED ON ORIGINAL FORMAT DRAWINGS. LOW 1600 668,000 670,000 672,000 674,000 676,000 SCALE: PROJECT: NOTES: 1:25,000 WESTERN ALBERTA SYSTEM MAINLINE LOOP 2 1. ALL DIMENSIONS ARE IN METRES UNLESS OTHERWISE NOTED. 7. UNLESS BGC AGREES OTHERWISE IN WRITING, THIS DRAWING SHALL NOT BE MODIFIED OR USED FOR ANY PURPOSE ALBERTA BRITISH COLUMBIA SECTION - 2. THIS DRAWING MUST BE READ IN CONJUNCTION WITH BGC'S REPORT TITLED "NOVA GAS TRANSMISSION LTD. - OTHER THAN THE PURPOSE FOR WHICH BGC GENERATED IT. BGC SHALL HAVE NO LIABILITY FOR ANY DAMAGES OR LOSS DATE: MAY 2020 BGC ENGINEERING INC. WESTERN ALBERTA SYSTEM MAINLINE LOOP 2 ALBERTA BRITISH COLUMBIA SECTION - DESKTOP ARISING IN ANY WAY FROM ANY USE OR MODIFICATION OF THIS DOCUMENT NOT AUTHORIZED BY BGC. ANY USE OF OR DESKTOP GEOHAZARDS PRELIMINARY ASSESSMENT AN APPLIED EARTH SCIENCES COMPANY GEOHAZARDS PRELIMINARY ASSESSMENT", AND DATED MAY 2020. RELIANCE UPON THIS DOCUMENT OR ITS CONTENT BY THIRD PARTIES SHALL BE AT SUCH THIRD PARTIES' SOLE RISK. DRAWN: B G C TITLE: 3. HILLSHADE BASED ON LIDAR PROVIDED BY AIRBORNE IMAGING DATED JULY 2010 AND GEOBASE CDED DEM STT SUBSIDENCE HAZARDS DATED 2018. CONTOUR INTERVAL IS 25 m. CLIENT: CHECKED: 4. ALBERTA BRITISH COLUMBIA SECTION ALIGNMENT REV 2 PROVIDED BY TC ENERGY ON APRIL 9, 2020. LGT PROJECT No.: DWG No: 5. WATERCOURSE AND WATERBODY DATA FROM GEOBASE NATIONAL HYDRO NETWORK. 6. HORIZONTAL PROJECTION IS NAD 1983 UTM ZONE 11. VERTICAL DATUM IS UNKNOWN. APPROVED: 0098187 08 MZ NOVA GAS TRANSMISSION LTD. (NGTL)

JuneX:\Projects\0098\187\GIS\Production\20200427_WASML_Loop2_Alberta_Section\ABC\08_Subsidence_Hazards.mxd 2020 Page 105 of 132 NOVA Gas Transmission Ltd. Attachment 6

NGTL West Path Delivery 2022 668,000 670,000 672,000 674,000 Desktop1600 Geohazards676,000 Preliminary Assessment INSET VIEW OF THE SOUTHEAST CORNER OF BRITISH COLUMBIA (CROWSNEST AREA) 1900

Kimberley ! HY22 HY95A ALBERTA HY3 Cranbrook Fernie ! ! ABC HY93 SECTION 1500 2100 ³ 5,504,000 1600 5,504,000 1700

1800 1900 BRITISH 2000

2200 HY95 2300 2400 COLUMBIA 2400 2400

1500 HW93 HY3 KOOTENAY HY95 LAKE ! PHILLIPPS PEAK

1500

5,502,000 5,502,000

! ALBERTA 4+000 4+500 ! 3+500 !

BRITISH COLUMBIA 5+000 ! ! ! 3+000 5+211 ! PHILLIPPS 1400 2+500 2+000 LAKE ! 1+500 !

1+000 ! 0+500 ! 1800 1500 CROWSNEST ! 0+000 LAKE 1700

1600 LEGEND

! KILOMETRE POST PROPOSED PIPELINE SENTINEL SECTIONS TC WESTERN SYSTEM CROWSNEST RIVER 5,500,000 STREAM 5,500,000 ROAD EMERALD ISLAND LAKE LAKE CROWSNEST HWY 3 1400 1400 SCALE 1:25,000 WATERBODY 250 0 250 500 750 1500 DESKTOP GEOTECHNICAL 1400 HAZARD RATING 1600 METRES (PROBLEMATIC/ORGANIC 1700 SOILS, PERMAFROST) THIS DRAWING1500 MAY HAVE BEEN REDUCED OR ENLARGED. ALL FRACTIONAL SCALE NOTATIONS INDICATED ARE 1800 BASED ON ORIGINAL FORMAT DRAWINGS. MODERATE 1600 668,000 670,000 672,000 674,000 676,000 SCALE: PROJECT: NOTES: 1:25,000 WESTERN ALBERTA SYSTEM MAINLINE LOOP 2 1. ALL DIMENSIONS ARE IN METRES UNLESS OTHERWISE NOTED. 7. UNLESS BGC AGREES OTHERWISE IN WRITING, THIS DRAWING SHALL NOT BE MODIFIED OR USED FOR ANY PURPOSE ALBERTA BRITISH COLUMBIA SECTION - 2. THIS DRAWING MUST BE READ IN CONJUNCTION WITH BGC'S REPORT TITLED "NOVA GAS TRANSMISSION LTD. - OTHER THAN THE PURPOSE FOR WHICH BGC GENERATED IT. BGC SHALL HAVE NO LIABILITY FOR ANY DAMAGES OR LOSS DATE: MAY 2020 BGC ENGINEERING INC. WESTERN ALBERTA SYSTEM MAINLINE LOOP 2 ALBERTA BRITISH COLUMBIA SECTION - DESKTOP ARISING IN ANY WAY FROM ANY USE OR MODIFICATION OF THIS DOCUMENT NOT AUTHORIZED BY BGC. ANY USE OF OR DESKTOP GEOHAZARDS PRELIMINARY ASSESSMENT AN APPLIED EARTH SCIENCES COMPANY GEOHAZARDS PRELIMINARY ASSESSMENT", AND DATED MAY 2020. RELIANCE UPON THIS DOCUMENT OR ITS CONTENT BY THIRD PARTIES SHALL BE AT SUCH THIRD PARTIES' SOLE RISK. DRAWN: B G C TITLE: 3. HILLSHADE BASED ON LIDAR PROVIDED BY AIRBORNE IMAGING DATED JULY 2010 AND GEOBASE CDED DEM STT GEOTECHNICAL HAZARDS DATED 2018. CONTOUR INTERVAL IS 25 m. CLIENT: CHECKED: 4. ALBERTA BRITISH COLUMBIA SECTION ALIGNMENT REV 2 PROVIDED BY TC ENERGY ON APRIL 9, 2020. LGT PROJECT No.: DWG No: 5. WATERCOURSE AND WATERBODY DATA FROM GEOBASE NATIONAL HYDRO NETWORK. 6. HORIZONTAL PROJECTION IS NAD 1983 UTM ZONE 11. VERTICAL DATUM IS UNKNOWN. APPROVED: 0098187 09 DG NOVA GAS TRANSMISSION LTD. (NGTL)

JuneX:\Projects\0098\187\GIS\Production\20200427_WASML_Loop2_Alberta_Section\ABC\09_Geotechnical_Hazards.mxd 2020 Page 106 of 132 NOVA Gas Transmission Ltd. Attachment 6

NGTL West Path Delivery 2022 668,000 670,000 672,000 674,000 Desktop1600 Geohazards676,000 Preliminary Assessment INSET VIEW OF THE SOUTHEAST CORNER OF BRITISH COLUMBIA (CROWSNEST AREA) 1900

Kimberley ! HY22 HY95A ALBERTA HY3 Cranbrook Fernie ! ! ABC

HY93 SECTION 1500 1500 2100 ³ 5,504,000 1600 5,504,000 1700

1800 1900 BRITISH 2000

2200 HY95 2300 2400 COLUMBIA 2400 2400

1500 HW93 HY3 KOOTENAY HY95 LAKE ! PHILLIPPS PEAK

")

") ")

DFSA KVB 5,502,000 5,502,000 ") ") ! ALBERTA 4+000 4+500 ! 3+500 ") ! BRITISH COLUMBIA ! ! DP KWpT 14 ! 5+000 3+000 5+211 ! KBsC PHILLIPPS ") 1400 2+500 2+000 LAKE ! 1+500 !

MMH DMEB ") 1+000 MLv ! 0+500 ! 1800 1500 CROWSNEST ! LAKE 0+000 1700

1600 ") ") ")

") ") SENTINEL LEGENDCFW CROWSNEST RIVER ! KILOMETRE POST MINERAL OCCURENCES BEDROCK GEOLOGY LIVINGSTONE FORMATION (MLv) 5,500,000 SULPHIDE/METAL VIRGELLE, DEADHORSE 5,500,000 PROPOSED PIPELINE ") OCCURRENCES COULEE, AND PAKOWKI EXSHAW AND BANFF EMERALD SECTIONS FORMATIONS, AND BELLY FORMATIONS (DMEB) ISLAND LAKE LAKE TC WESTERN SYSTEM NON-SULPHIDE/METAL 1400 ") RIVER GROUP (KVB) 1400 OCCURENCES PALLISER FORMATION (DP) SCALE 1:25,000 STREAM WAPIABI AND TELEGRAPH 250 0 250 500 750 1500 DESKTOP GEOCHEMICAL CREEK FORMATIONS (KWpT) FAIRHOLME GROUP AND ROAD HAZARD RATING SASSENACH AND ALEXO 1400 1600 METRES CROWSNEST HWY 3 BLACKSTONE AND CARDIUM FORMATIONS (DFSA) MODERATE FORMATIONS (KBsC) 1700 FLATHEAD, GORDON, ELKO, THIS DRAWING1500 MAY HAVE BEEN REDUCED OR ENLARGED. WATERBODY MOUNT HEAD FORMATION AND WINDSOR MOUNTAIN ALL FRACTIONAL SCALE NOTATIONS INDICATED ARE 1800 LOW BASED ON ORIGINAL FORMAT DRAWINGS. (MMH) FORMATIONS (CFW) 1600 668,000 670,000 672,000 674,000 676,000 NOTES: SCALE: PROJECT: 1:25,000 WESTERN ALBERTA SYSTEM MAINLINE LOOP 2 1. ALL DIMENSIONS ARE IN METRES UNLESS OTHERWISE NOTED. 6. WATERCOURSE AND WATERBODY DATA FROM GEOBASE NATIONAL HYDRO NETWORK. ALBERTA BRITISH COLUMBIA SECTION - 2. THIS DRAWING MUST BE READ IN CONJUNCTION WITH BGC'S REPORT TITLED "NOVA GAS TRANSMISSION LTD. - 7. THE GEOCHEMICAL HAZARD RATING DISPLAYED DOES NOT INTEGRATE THE LIKELIHOOD OF INTERSECTING SHALLOW DATE: MAY 2020 BGC ENGINEERING INC. DESKTOP GEOHAZARDS PRELIMINARY ASSESSMENT WESTERN ALBERTA SYSTEM MAINLINE LOOP 2 ALBERTA BRITISH COLUMBIA SECTION - DESKTOP BEDROCK ALONG THE ALIGNMENT. GEOHAZARDS PRELIMINARY ASSESSMENT", AND DATED MAY 2020. AN APPLIED EARTH SCIENCES COMPANY 8. HORIZONTAL PROJECTION IS NAD 1983 UTM ZONE 11. VERTICAL DATUM IS UNKNOWN. DRAWN: B G C TITLE: 3. HILLSHADE BASED ON LIDAR PROVIDED BY AIRBORNE IMAGING DATED JULY 2010 AND GEOBASE CDED DEM STT GEOCHEMICAL HAZARDS MAP DATED 2018. CONTOUR INTERVAL IS 25 m. 9. UNLESS BGC AGREES OTHERWISE IN WRITING, THIS DRAWING SHALL NOT BE MODIFIED OR USED FOR ANY PURPOSE CLIENT: OTHER THAN THE PURPOSE FOR WHICH BGC GENERATED IT. BGC SHALL HAVE NO LIABILITY FOR ANY DAMAGES OR LOSS CHECKED: 4. BEDROCK GEOLOGY DATA IS FROM THE STOCKMAL AND FALLAS (2015) GEOLOGICAL MAP AND MINERAL LGT PROJECT No.: DWG No: OCCURRENCE DATA IS FROM THE ALBERTA DEPARTMENT OF ENERGY METALLIC AND ARISING IN ANY WAY FROM ANY USE OR MODIFICATION OF THIS DOCUMENT NOT AUTHORIZED BY BGC. ANY USE OF OR INDUSTRIAL MINERALS ACTIVITY MAP RELIANCE UPON THIS DOCUMENT OR ITS CONTENT BY THIRD PARTIES SHALL BE AT SUCH THIRD PARTIES' SOLE RISK. APPROVED: 0098187 10 5. ALBERTA BRITISH COLUMBIA SECTION ALIGNMENT REV 2 PROVIDED BY TC ENERGY ON APRIL 9, 2020. SB NOVA GAS TRANSMISSION LTD. (NGTL)

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APPENDIX A DESCRIPTIVE LIST OF ALL GEOHAZARD CLASSES AND TYPES

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Table A-1. Descriptive list of all geohazard types included in this assessment, including comments on occurrence and impact. Construction- Natural Possible Project Third-Party Impacts Geohazard Description induced occurrences Impacts from Project occurrences Landslide Rock fall Fragments or large mass of Steep rock slopes Steep rock cuts Buried and above-ground Above-ground rock detach from a steep infrastructure. infrastructure located rock face and travel Construction safety. downslope of RoW grade downslope independently cuts with a free falling, bouncing, or rolling motion. Includes seismically triggered events.

Rockslide Fragments or large mass of Steep rock slopes Steep rock cuts Buried and above-ground Above-ground rock detach from a steep infrastructure. infrastructure located rock face and travel Construction safety. downslope of RoW grade downslope rapidly as a cuts coherent mass before breaking up with increased travel distance from the source area. Includes seismically triggered events.

Rock avalanche Large coherent rock mass Steep distressed N/A Buried and above-ground N/A releases from a steep mountain slopes infrastructure mountainside, breaking up and developing flow-like behavior and long travel distance. Includes seismically triggered events.

Appendix A - Descriptive List of all Geohazard Classes and Types A-1 BGC ENGINEERING INC.

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Construction- Natural Possible Project Third-Party Impacts Geohazard Description induced occurrences Impacts from Project occurrences Earth landslide A mass of soil or very weak, Slopes with Cut slopes in Buried and above-ground Buried and above-ground highly weathered rock that unstable rock or unstable rock or soil. infrastructure infrastructure. Release of moves primarily by sliding soil Fill placed on debris from the RoW on a basal shear surface, unstable rock or soil. outside of permitted potentially accompanied by Thawing workspace. internal deformation. winter-placed fill. Includes all deep-seated, slowly and rapidly moving landslides in soil or very weak rock. Often associated with saturation with water. May accelerate and move suddenly several meters or tens of meters or develop flow-like behaviour. Includes earth flow/slide/spread/slump. Includes seismically triggered events.

Appendix A - Descriptive List of all Geohazard Classes and Types A-2 BGC ENGINEERING INC.

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Construction- Natural Possible Project Third-Party Impacts Geohazard Description induced occurrences Impacts from Project occurrences Debris A shallow layer of weak soil Steep slopes Steep soil cuts. Fill Above-ground Above-ground slide/avalanche or weathered rock overlying (particularly those placed on steep infrastructure for upslope infrastructure located more competent soil or with existing scars slopes with loose sources. Buried and downslope of RoW bedrock that detaches and locally) overburden soils, or above-ground slides rapidly down a steep due to alteration of infrastructure for RoW slope. Debris surface or sources. slides/avalanches may near-surface entrain additional material as drainage they slide down slope and can evolve into debris flows if they enter a channel with sufficient water. Includes seismically triggered events.

Snow/ice avalanche Extremely rapid to rapid Steep, Steep cut slopes Above-ground N/A release of snowpack layers snow-covered may be capable of infrastructure. or seasonal/glacial ice and slopes producing snow Construction safety. snow which break up and avalanches develop flow-like behaviour and long runouts. May be wet or dry.

Debris flow Granular debris/water mixed Steep creeks and N/A Buried and above-ground N/A flows (debris dominated) colluvial/alluvial infrastructure which emanate from upslope fans basins or existing aggraded channels and run onto lower angle terrain, forming colluvial cones and fans.

Appendix A - Descriptive List of all Geohazard Classes and Types A-3 BGC ENGINEERING INC.

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Construction- Natural Possible Project Third-Party Impacts Geohazard Description induced occurrences Impacts from Project occurrences Debris flood Granular debris/water mixed Steep creeks, N/A Buried and above-ground N/A flows (water dominated) alluvial fans and infrastructure which emanate from upslope some floodplains basins and run onto lower angle terrain, forming alluvial fans.

Outburst flood Debris-rich flows in existing Floodplains N/A Buried and above-ground N/A river network generated by downstream from infrastructure sudden release and rapid dammed lakes drainage of upstream storage in landslide- dammed, moraine-dammed, beaver-dammed, proglacial or subglacial lakes.

Hydrotechnical Scour of the channel Scour can happen at any Channel bed Changes to the Buried infrastructure Nearby in-stream bed location where local flow elevation and within channel infrastructure velocities increase as a erodibility of the result of secondary currents channel bed. developing within a uniform Changes to the flow situation. Scour also channel occurs when the direction of cross-section. flow is changed at channel bends, confluences, constrictions, obstructions, and impingements. Scour is considered event-based.

Appendix A - Descriptive List of all Geohazard Classes and Types A-4 BGC ENGINEERING INC.

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Construction- Natural Possible Project Third-Party Impacts Geohazard Description induced occurrences Impacts from Project occurrences Degradation of the Degradation is the process Channel bed Changes to the Buried infrastructure Nearby in-stream channel bed of a general lowering of the elevation and within channel. infrastructure channel bed and is the result erodibility of the of the process of channel channel bed. morphology reaching Changes to the equilibrium with the existing channel cross- flow regime (Ulrich et al., section. 2005). Diversion of additional discharge to the channel.

Bank erosion Patterns of sediment Channel banks Change in the Buried and above-ground Nearby in-stream (pipeline alignment transport and deposition erodibility of bank infrastructure. infrastructure. Above- traverses the naturally cause the channel material. ground infrastructure watercourse). banks to migrate laterally, Change in the located in the riparian Encroachment (bank resulting in bank erosion. alignment of the area. erosion where the watercourse. pipeline alignment is Change in the bank adjacent to the shape. watercourse)

Avulsion Avulsion, also referred to as Alluvial fans Diversion channels Buried and above-ground Nearby in-stream outflanking, or Wide floodplains created to aid in infrastructure. infrastructure such as abandonment, occurs when construction not pipelines. streams leave their present adequately Stream crossings located channel and establish a new rehabilitated. on the avulsion channel. channel. Any infrastructure located on the alluvial fan or floodplain.

Appendix A - Descriptive List of all Geohazard Classes and Types A-5 BGC ENGINEERING INC.

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Construction- Natural Possible Project Third-Party Impacts Geohazard Description induced occurrences Impacts from Project occurrences Seismic Seismic ground Ground shaking due to Seismic hazard N/A Buried and above-ground N/A shaking earthquake. zones, areas of infrastructure. oil/gas extraction

Seismic liquefaction Liquefaction and differential Saturated, N/A Buried and above-ground N/A movement of foundation cohesionless soils infrastructure. soils due to earthquake shaking (subsidence, buoyancy, lateral spreading and flow sliding).

Surface fault rupture Differential movement Faults N/A Buried infrastructure. N/A across the surface expression of faults during earthquakes.

Subsidence

Karst subsidence Vertical movement collapse Soluble bedrock N/A Buried and above-ground N/A or loss of foundation soils infrastructure, potential due to presence of negative effects to karst subsurface voids, caves, resources. caverns in soluble bedrock. Safety risk to heavy equipment during construction.

Mine subsidence Vertical movement collapse Areas of N/A Buried and above-ground N/A or loss of foundation soils underground infrastructure. due to the presence of mining Safety risk to heavy subsurface mine workings. equipment during construction.

Appendix A - Descriptive List of all Geohazard Classes and Types A-6 BGC ENGINEERING INC.

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Construction- Natural Possible Project Third-Party Impacts Geohazard Description induced occurrences Impacts from Project occurrences Thick compressible Vertical movement caused Thick deposits of Winter-placed/poorly Buried and above-ground soils by the settling of a organics or young, compacted fill infrastructure. compressible layer. under-consolidated silt or clay.

Fluid-withdrawal Differential vertical Areas of oil/gas N/A Buried and above-ground N/A subsidence movement due to extraction, or large infrastructure. hydrocarbon extraction or water wells, groundwater withdrawal (high capacity water wells can cause widespread subsidence) nearby.

Geotechnical

Problematic Soils with a propensity to N/A Changes to water Buried and above-ground Buried and above-ground (Expansive or swell or collapse with content in fine- infrastructure. infrastructure collapsible) soils changes in water content, grained soils and associated stability challenges.

Permafrost Unstable conditions induced Alpine permafrost Excavation or Buried and above-ground Buried and above-ground degradation by thawing of permafrost. disturbance in alpine infrastructure. infrastructure permafrost

Peat/organic soils Organic soils and associated Peat Excavation in peat Buried and above-ground N/A poor foundation conditions, infrastructure. including buoyancy and subsidence issues.

Geochemical ARD-ML Acid rock drainage and/or N/A Excavation into or N/A Environmental metal leaching. exposure of acid- generating bedrock

Appendix A - Descriptive List of all Geohazard Classes and Types A-7 BGC ENGINEERING INC.

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APPENDIX B RATIONALE FOR CLASSIFICATION FOR LANDSLIDE, SUBSIDENCE, GEOTECHNICAL, AND SEISMIC HAZARDS RATING

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Table B-1. Rationale for hazard classification of landslide, subsidence, geotechnical, and seismic hazards. Hazard Rating Low: Standard Moderate: Field review High: Detailed field review Geohazard Non-credible: Hazard not construction practice and typical mitigations and site-specific present or not a threat likely adequate to likely required mitigation likely required manage the hazard Landslide Rock fall Rockfall sources not present at Engineered cuts or potential Rockfall sources above the Rockfall sources above RoW or above RoW natural source areas above RoW with some evidence of with evidence of large rockfalls RoW with limited evidence of past rockfall activity in the reaching the RoW past rockfall activity in the vicinity of the RoW vicinity of the RoW

Rock slide Rockslide sources not present Engineered cuts or natural Evidence of past rockslide Evidence of recent or incipient above RoW source areas with some events that reached the RoW rockslides that could reach the potential to produce rockslides or close to it RoW in the vicinity of the RoW

Rock avalanche Rock avalanche sources not Steep rocky mountain tops Evidence of past or potential Evidence of recent or incipient present above the RoW above the RoW with unknown rock avalanche rock avalanches that could potential to produce rock occurrence that could reach reach RoW avalanches RoW

Earth landslide Slopes with landside-prone Slopes and landslide-prone Evidence of past landslide Fresh or incipient landslides materials not present materials present at or above activity at or adjacent to the present at or adjacent to the RoW but no evidence of RoW RoW previous landslide activity

Debris Debris slide/avalanche Steep slopes with potential Evidence of debris slide scars Evidence of frequent or slide/avalanche sources not present above the debris veneer present above present on slopes above RoW repeated debris slides reaching RoW the RoW the RoW

Snow/ice avalanche Avalanche paths/terrain not Steep slopes with potential to Defined snow avalanche paths Defined snow avalanche paths present at or above RoW release avalanches above adjacent to RoW/valve reach the RoW/valve locations RoW/valve locations locations

Appendix B - Rationale for Classification B-1 BGC ENGINEERING INC.

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Hazard Rating Low: Standard Moderate: Field review High: Detailed field review Geohazard Non-credible: Hazard not construction practice and typical mitigations and site-specific present or not a threat likely adequate to likely required mitigation likely required manage the hazard Debris flow Steep creek and/or colluvial Steep creek with limited debris Steep creek with potential Steep creek with debris source fan/cone not present at RoW source and no colluvial fan source area and inactive and active colluvial fan deposit deposit colluvial fan deposit

Debris flood Steep creek and alluvial fan Steep creek with limited debris Steep creek with potential Steep creek with debris source not present at RoW source and no alluvial fan source area and inactive and active alluvial fan deposit deposit alluvial fan deposit

Outburst flood No landslide or Mature moraine or landslide N/A Fresh or eroding moraine or moraine-dammed lake dammed lake upstream of landslide dammed lake upstream of RoW right of way upstream of RoW

Subsidence Karst subsidence Soluble bedrock not present Soluble bedrock present; no Soluble bedrock present; Soluble bedrock and confirmed subsidence features identified potential karst subsidence karst features present nearby features nearby

Mine subsidence No known mine workings in Potential shallow mine Known mine workings Recognized mine subsidence in area workings underlying RoW underlying RoW vicinity of RoW

Thick compressible No deposits of organics or Potentially compressible soils Compressible soils present in Evidence of thick compressible soils young, under-consolidated silt present in limited thickness limited thickness and extent soils and past subsidence or clay and extent

Fluid-withdrawal No hydrocarbon or major Hydrocarbon or major Evidence of past subsidence Evidence of recent or incipient subsidence groundwater extraction nearby groundwater extraction in area events in the vicinity of subsidence events in vicinity of hydrocarbon or major hydrocarbon or major groundwater extractions groundwater extraction

Appendix B - Rationale for Classification B-2 BGC ENGINEERING INC.

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Hazard Rating Low: Standard Moderate: Field review High: Detailed field review Geohazard Non-credible: Hazard not construction practice and typical mitigations and site-specific present or not a threat likely adequate to likely required mitigation likely required manage the hazard Geotechnical Problematic Expansive/collapsible soils not Expansive/collapsible unlikely Expansive/collapsible soils Expansive/collapsible soils (Expansive or present be present identified in mapping present collapsible) soils

Permafrost Permafrost not present Permafrost possible based on Permafrost present in the area Permafrost present at RoW degradation aspect/elevation of the RoW

Peat/organic soils Peat/organic soils not present Thin or sporadic peat/organic Peat/organic soils of limited Thick, extensive peat/organic soils may be present thickness and extent identified deposits present in mapping

Seismic Liquefaction No liquefaction susceptibility Low relative liquefaction Moderate relative liquefaction High relative liquefaction hazard: hazard: hazard:  All susceptibility classes  High susceptibility where  High susceptibility where where 1:2475 PGA<0.1g 0.1g≤1:2475 PGA<0.2g 1:2475 PGA≥0.2g  Low and moderate  Moderate susceptibility susceptibility where where 1:2475 PGA≥0.2g 0.1g≤1:2475 PGA<0.2g  Low susceptibility where 1:2475 PGA≥0.2g

Appendix B - Rationale for Classification B-3 BGC ENGINEERING INC.

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Hazard Rating Low: Standard Moderate: Field review High: Detailed field review Geohazard Non-credible: Hazard not construction practice and typical mitigations and site-specific present or not a threat likely adequate to likely required mitigation likely required manage the hazard Surface faulting No mapped faults or Mapped pre-Quaternary Any of the following: Any of the following: observable lineaments bedrock fault with no  Mapped pre-Quaternary  Mapped Quaternary fault associated observable bedrock fault with no  Observable topographic topographic lineament in an associated observable lineament that offsets area with LiDAR coverage topographic lineament in Quaternary sediments an area with no LiDAR  Historical seismicity coverage concentrated along a  Mapped pre-Quaternary mapped Quaternary or bedrock fault with an pre-Quaternary fault associated observable topographic lineament in an area with LiDAR coverage, where the lineament is truncated by Pleistocene (glacial) or older deposits

Co-seismic landslides Nothing above class1 1-3 Some 4 Lots of class 4-5

Appendix B - Rationale for Classification B-4 BGC ENGINEERING INC.

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APPENDIX C LANDSLIDE HAZARDS INVENTORY

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Table C-1. Landslide hazard inventory. Chainage (080424-2020-SH-08-0001 Coordinates in UTM NAD 83 Zone 11U (m) Length Hazard Rev 2) Hazard Type Comments (m) Rating Geohazard From From To To From To ID Northing Easting Northing Easting

C-L-01 2+650 2+850 200 5501609 671648 5501672 671465 Outburst Flood Low Small lake is impounded by mature moraine, which is cut by creek draining lake.

C-L-02 3+100 3+225 125 5501680 671219 5501681 671110 Rockfall Low Ascent slope with some potential rockfall sources identified in LiDAR and imagery.

C-L-03 3+400 3+500 100 5501764 670971 5501768 670871 Rockfall Moderate Sidehill section with possible cuts and potential upslope sources. Talus present.

Exposed to potential avalanche terrain through this segment. Micro-positioning of above C-L-04 3+400 5+211 1811 5501768 670871 5501898 670033 Snow avalanche Low ground infrastructure may be required. Worker safety hazard in avalanche season.

C-L-05 3+500 3+535 35 5501768 670871 5501769 670837 Rockfall Moderate Sidehill below exposed rock face with potential upslope sources. Talus present.

C-L-06 3+875 3+925 50 5501785 670500 5501789 670451 Rockfall Moderate Sidehill across coarse talus with potential upslope sources.

C-L-07 4+075 4+200 125 5501808 670307 5501808 670307 Rockfall Low Sidehill below exposed rock face with potential upslope sources. Talus present.

C-L-08 4+200 4+380 180 5501898 670033 5501899 670023 Rockfall Moderate Sidehill below high rockfall source with evidence of past rockfalls.

C-L-09 4+380 4+610 230 5501899 670023 5501851 669810 Rockfall Moderate Sidehill with possible cuts and potential sources upslope. Talus likely present.

C-L-10 4+380 4+575 195 5501899 670023 5501858 669834 Rockslide Low Potential source above RoW.

Clearly distressed upper dip-slopes on Mt. Tecumseh with evidence of past rockslides. C-L-11 4+475 4+675 200 5501883 669931 5501851 669810 Rock avalanche Moderate Flow-like runout could reach right of way.

Possible exposure to large debris flows from north side of valley extending beyond C-L-12 4+530 4+600 70 5501871 669878 5501851 669810 Debris flow Low inactive, small fan.

Exposure to large debris flows from north side of valley extending beyond inactive, large C-L-13 4+600 5+211 611 5501851 669810 5501851 669810 Debris flow Moderate fan with debris source.

C-L-14 4+775 5+211 436 5501792 669647 5501792 669647 Debris slide Moderate Scars from past debris slides above right of way. RoW potentially in deposition zone.

Appendix C - Landslide Hazard Inventory C-1 BGC ENGINEERING INC.

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APPENDIX D HYDROTECHNICAL HAZARDS INVENTORY

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Table D-1. Hydrotechnical hazard inventory. Coordinates in UTM Chainage NAD 83 Zone 11U Crossing Stream Regional Bankfull Local Hazard Site ID Local Ephemeral Geohazard ID (080424-2020-SH- (m) Hazard Type Observations Information Class Channel Width Channel Rating (Midwest) Geometry Flow 08-0001 Rev 2) Northing Easting (Midwest) (Midwest) Pattern (m) Gradient

WX-045 – B1 - Single Unnamed 107.00- Channel - Severe C-H-1 0+400 5500891 5500891 Crossing Moderate Watercourse not visible in imagery Tributary Tributary to No 4.5 0.04 WC Moderate Bend Crowsnest Sinuosity River

A - Single Short flowpath emptying into a Channel - C-H-2 2+190 5501447 5501447 Crossing Moderate - - - Straight No 12.2 0.07 lake Low Sinuosity

Stantec Enviro survey, Oct 22, 2019: Habitat characteristics at centerline have stream morphology, however, 250 m WX-046 - A - Single downstream of centerline the Unnamed 114.00- Channel - C-H-3 2+671 5501617 5501617 Crossing Low channel losses it's stream Intermittent Tributary to Straight Yes 0.8 0.07 WC Low morphology and transitions into a Crowsnest Sinuosity drainage. Fish passage is Lake restricted due to the drainage morphology. Direction of flow: south.

A - Single 118.00- WX-044 - Channel - C-H-4 3+521 5501769 5501769 Crossing Low Ephemeral Straight Yes 1.1 0.07 WC Drainage Low Sinuosity

RNT identified stream running parallel to road and alignment, no A - Single visible banks within large Channel - Gentle C-H-5 3+800 5501782 5501782 Encroachment Moderate - - No 0.11 floodplain. Approximately 85 m of Low Bend encroachment hazard two Sinuosity crossings

A - Single Stream encroaches within 8 m of Channel - C-H-6 5+200 5501598 5501598 Encroachment Moderate end of alignment, which is up on - - - Straight Yes 3.2 0.02 Low the left bank Sinuosity

Appendix D - Hydrotechnical Hazard Inventory D-1 BGC ENGINEERING INC.

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APPENDIX E SEISMIC HAZARDS INVENTORY

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Table E-1. Seismic hazard inventory. Chainage (080424-2020-SH-08-0001 Coordinates in UTM NAD 83 Zone 11U (m) Length Hazard Rev 2) Hazard Type Comments (m) Rating Geohazard From From To To From To ID Northing Easting Northing Easting

C-Se-01 0+000 1+420 1420 5500849 674143 5501212 672790 Liquefaction Low

C-Se-02 2+080 3+110 1030 5501443 672178 5501680 671210 Liquefaction Low

C-Se-03 3+060 3+140 80 5501680 671259 5501681 671185 Landslide Moderate

Lewis Thrust. Masked by early Holocene moraines to the south and Pleistocene till C-Se-04 3+100 3+100 0 5501680 671219 5501680 671219 Surface faulting Low through corridor and to the north. Expressed as sharp, west-facing bedrock cliffs. No co-located historical seismicity.

Masked by Pleistocene till blankets to the north and Holocene colluvium. Bedding- C-Se-05 3+500 3+500 0 5501768 670871 5501768 670871 Surface faulting Low parallel, curvilinear expression. No co-located historical seismicity.

C-Se-06 3+500 3+800 300 5501768 670871 5501782 670574 Landslide Moderate

C-Se-07 3+530 3+780 250 5501769 670842 5501781 670593 Liquefaction Low

Truncated by uniform bedding to the north. Masked by Holocene colluvium and valley fill. C-Se-08 3+710 3+710 0 5501774 670663 5501774 670663 Surface faulting Low Discontinuous, bedding-parallel lineaments. Truncated by colluvium and rock fall deposits to the south. No co-located historical seismicity.

C-Se-09 3+800 4+000 200 5501782 670574 5501796 670380 Landslide Low

C-Se-10 3+980 4+370 390 5501794 670399 5501898 670033 Liquefaction Low

C-Se-11 4+000 4+800 800 5501796 670380 5501779 669625 Landslide High

C-Se-12 4+600 5+211 611 5501851 669810 5501595 669265 Liquefaction High

Truncated by uniform bedding to the north. Masked by Holocene colluvium and valley fill. C-Se-13 4+610 4+610 0 5501848 669801 5501848 669801 Surface faulting Low Defined by bedding planes. Concealed by Pleistocene glaciofluvial terraces and Holocene alpine moraines and valley fill to the south. No co-located historical seismicity.

C-Se-14 4+800 5+211 411 5501779 669625 5501595 669265 Landslide Moderate

Appendix E - Seismic Hazard Inventory E-1 BGC ENGINEERING INC.

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APPENDIX F SUBSIDENCE HAZARDS INVENTORY

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NOVA Gas Transmission Ltd., WASML Loop No. 2 Alberta British Columbia Section (ABC Section) May 27, 2020 Desktop Geohazards Preliminary Assessment – REV 1 Project No.: 0098187

Table F-1. Subsidence hazard inventory. Chainage (080424-2020-SH-08-0001 Coordinates in UTM NAD 83 Zone 11U (m) Length Hazard Rev 2) Hazard Type Comments (m) Rating Geohazard From From To To From To ID Northing Easting Northing Easting Soluble bedrock underlying RoW (Belly River and Alberta Gp.), but beneath thick C-S-01 0+000 4+600 4600 5500849 674143 5501768 670871 Karst Low surficial deposits.

Soluble bedrock underlying RoW (Banff/Rundle Fm., other Devonian), variably exposed C-S-02 4+600 5+211 611 5501768 670871 5501595 669265 Karst Moderate or buried by surficial deposits. Karst features identified by Ford (1979) on upper ridges, and springs in valley bottom. 400 m from Phillipps Lake (karstic).

Appendix F - Subsidence Hazard Inventory F-1 BGC ENGINEERING INC.

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APPENDIX G GEOTECHNICAL HAZARDS INVENTORY

June 2020 Page 129 of 132 NOVA Gas Transmission Ltd. Attachment 6 NGTL West Path Delivery 2022 Desktop Geohazards Preliminary Assessment

NOVA Gas Transmission Ltd., WASML Loop No. 2 Alberta British Columbia Section (ABC Section) May 27, 2020 Desktop Geohazards Preliminary Assessment – REV 1 Project No.: 0098187

Table G-1. Geotechnical hazard inventory. Chainage (080424-2020-SH-08-0001 Coordinates in UTM NAD 83 Zone 11U (m) Length Hazard Rev 2) Hazard Type Comments (m) Rating Geohazard From From To To From To ID Northing Easting Northing Easting

C-G-01 0+000 1+400 1400 5500849 674143 5501205 672808 Peat/organic soils Moderate Zone containing several intersections with organic soils and wetlands in terrain mapping.

C-G-02 2+500 2+530 30 5501553 671784 5501564 671756 Peat/organic soils Moderate Intersection with small wetland/peat area.

Appendix G - Geotechnical Hazard Inventory G-1 BGC ENGINEERING INC.

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APPENDIX H GEOCHEMICAL HAZARDS INVENTORY

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NOVA Gas Transmission Ltd., WASML Loop No. 2 Alberta British Columbia Section (ABC Section) May 27, 2020 Desktop Geohazards Preliminary Assessment – REV 1 Project No.: 0098187

Table H-1. Geochemical hazard inventory. Chainage (080424-2020-SH-08-0001 Coordinates in UTM NAD 83 Zone 11U (m) Length Hazard Rev 2) Hazard Type Comments (m) Rating Geohazard From From To To From To ID Northing Easting Northing Easting Sulphide/metal occurrence within 2 km of the alignment and, intersections with C-Gc-01 0+000 3+500 3500 5500849 674143 5501768 670871 ARD/ML Moderate coal-bearing formations.

C-Gc-02 3+500 5+211 1711 5501768 670871 5501595 669264 ARD/ML Low Calcareous sediments with no metal or sulphide bearing mineral occurrences.

Appendix H - Geochemical Hazard Inventory H-1 BGC ENGINEERING INC.

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