Geotechnical Investigation Report

Geotechnical Investigation Report

Proposed NPS 10 & NPS 20 Pipeline Installations Queen Elizabeth Way (QEW) Crossings

Project No. 160950937 Document No. TAJ-C-GEO-001

Queen Elizabeth Way & Credit River Mississauga, ON

Prepared for: Trans-Northern Pipelines Inc.

Prepared by: Stantec Consulting Ltd. 300W-675 Cochrane Drive Markham, ON L3R 0B8

December 18, 2018

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Table of Contents

1.0 INTRODUCTION ................................................................................................................ 1

2.0 SITE DESCRIPTION AND GEOLOGY ................................................................................. 1 2.1 SITE LOCATION ..................................................................................................................... 1 2.2 SITE DESCRIPTION ................................................................................................................. 2 2.3 SUBSURFACE LITERATURE REVIEW ...................................................................................... 2

3.0 PROPOSED CROSSINGS ................................................................................................... 5 3.1 HDD ALIGNMENT AND PROFILE ......................................................................................... 5 3.2 TEMPORARY WORK SPACE ................................................................................................ 5 3.3 EXISTING STRUCTURES .......................................................................................................... 6

4.0 SCOPE OF WORK ............................................................................................................. 6

5.0 METHOD OF INVESTIGATION ........................................................................................... 7 5.1 FIELD INVESTIGATION ........................................................................................................... 7 5.2 SURVEYING ........................................................................................................................... 8 5.3 LABORATORY TESITNG ......................................................................................................... 9

6.0 SUBSURFACE CONDITIONS ............................................................................................ 10 6.1 FRAME OF REFERENCE ...................................................................................................... 10

6.1.1 Overburden ..................................................................................................... 10 6.1.2 Bedrock ............................................................................................................ 10

6.2 OVERVIEW ........................................................................................................................... 11 6.3 OVERBURDEN ..................................................................................................................... 11

6.3.1 Topsoil ............................................................................................................... 11 6.3.2 Granular Fill ...................................................................................................... 11 6.3.3 Silty Clayey Sand with Gravel (SC-SM) to Silty Sand (SM) ........................ 12 6.3.4 CLAY (CL) ......................................................................................................... 13

6.4 BEDROCK ............................................................................................................................ 14 6.4.1 Inferred Bedrock ............................................................................................. 14 6.4.2 Bedrock Core .................................................................................................. 14 6.4.3 Bedrock Properties .......................................................................................... 17

6.5 GROUNDWATER ................................................................................................................. 18

7.0 MISCELLANEOUS ............................................................................................................ 18

8.0 CLOSURE ......................................................................................................................... 18

9.0 DISCUSSION ................................................................................................................... 19 9.1 PROJECT DESCRIPTION AND BACKGROUND ................................................................ 19

9.1.1 Overall Project ................................................................................................. 19 9.1.2 Queen Elizabeth Way Crossing .................................................................... 19

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10.0 TRENCHLESS TECHNOLOGY INSTALLATION .................................................................. 21 10.1 OVERVIEW OF TRENCHLESS TECHNOLOGY METHODS ................................................ 21 10.2 HORIZONTAL DIRECTIONAL DRILLING ............................................................................. 23

10.2.1 Overview .......................................................................................................... 23

11.0 DESIGN CONSIDERARTIONS .......................................................................................... 25 11.1 ANTICIPATED STRATIGRAPHY ALONG THE HDD PATH FOR CONSTRUCTION ............ 25 11.2 FEASIBILITY OF HDD CONSTRUCTION .............................................................................. 25 11.3 CONTRAINTS AND LIMITATIONS OF HDD ........................................................................ 26 11.4 TUNNELMAN’S GROUND CLASSIFICATION & POTENTIAL SETTLEMENT ....................... 28 11.5 RECOMMENDATIONS ........................................................................................................ 30

11.5.1 Non-Standard Special Provision ................................................................... 30 11.5.2 Monitoring ........................................................................................................ 30

11.6 GEOTECHNICAL PARAMETERS FOR HDD ANALYSIS ..................................................... 31

12.0 CONSTRUCTION CONSIDERATIONS ............................................................................. 32 12.1 EXCAVATIONS AND DEWATERING .................................................................................. 32 12.2 TEMPORARY SHORING ...................................................................................................... 33 12.3 REMOVAL OF PROTECTIVE SYSTEMS AND BACKFILLING .............................................. 35 12.4 BEDDING AND BACKFILL................................................................................................... 35 12.5 ESTIMATES OF HYDRAULIC CONDUCTIVITY .................................................................... 35

13.0 SIGN-OFF SHEET ............................................................................................................. 37

LIST OF TABLES Table 2.1: Summary of GEOCRES Depths and Elevations of Weathered Shale ................... 4 Table 5.1: Borehole Location and Ground Surface Elevations ............................................... 9 Table 6.1: Typical Weathering Profile of Low Durability Shale ............................................... 10 Table 6.2: Grain Size Distribution – Silty Sand (SM) Fill .............................................................. 12 Table 6.3: Grain Size Distribution – Silty Clayey Sand to Silty Sand (SM) ............................... 12 Table 6.4: Atterberg Limits Tests Results –Clay to Clay with Gravel ....................................... 13 Table 6.5: Grain Size Distribution – Clay (CL) ............................................................................. 13 Table 6.6: Atterberg Limits Tests Results – Clay (CL) ................................................................. 14 Table 6.7: Inferred Highly to Completely Weathered Shale Bedrock .................................. 14 Table 6.8: Summary of Bedrock Coring Operations ................................................................ 15 Table 6.9: Results of Unconfined Compressive Strength (UCS) on Samples of Rock

Core .................................................................................................................................. 16 Table 6.10: Typical Physical Properties for the Georgian Bay Formation ............................. 17 Table 10.1: Comparison of Trenchless Technology Options .................................................. 21 Table 11.1: Risk Register for HDD Installation and Possible Impact to Infrastructure .......... 28 Table 11.2 Tunnelman’s Ground Classification and Probable Working Conditions .......... 29 Table 11.3 Geotechnical Parameters for HDD Analysis .......................................................... 31 Table 12.1: Soil Parameters for Design of Temporary Shoring System ................................. 34

LIST OF APPENDICES

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APPENDIX A Statement of General Conditions APPENDIX B Drawings APPENDIX C Symbols and Terms Used on Borehole Records

Borehole Records APPENDIX D Geotechnical Laboratory Test Results APPENDIX E Rock Core Logs APPENDIX F Non Standard Special Provision

GEOTECHNICAL INVESTIGATION REPORT DECEMBER 18, 2018

ha v:\01216\active\1609\160950937\reports\qew_crossing\160950937_geotech_rpt_hdd_qew_20181218.docx 1

GEOTECHNICAL INVESTIGATION REPORT Proposed Pipeline Installation – Crossing of the Queen Elizabeth Way (QEW)

Mississauga, Ontario

1.0 INTRODUCTION

Trans-Northern Pipelines Inc. (TNPI) intends to relocate two (2) pipelines (NPS 10 and NPS 20 inch) at the crossing of the Credit River. The relocations required are in response to a request from the Ontario Ministry of Transportation (MTO) to allow for the twinning of the Queen Elizabeth Way (QEW) bridge across the Credit River.

The relocations will require separate trenchless crossings of the QEW and the Credit River for each of the two pipelines.

Stantec Consulting Ltd. (Stantec) was retained by TNPI to complete a geotechnical investigation for the pipeline crossings. The investigation is required to determine the subsurface conditions at the crossing locations to assess the technical feasibility and to support the design and construction of the crossings.

This geotechnical report is specific to the QEW crossings, which is proposed to be completed via horizontal directional drilling (HDD). A geotechnical report for the Credit River crossings is provided under a separate cover.

The geotechnical investigation was completed in accordance with the proposal dated January 18, 2017, (Document No. 160950937), submitted to TNPI.

This report contains the factual results of the geotechnical investigation and provides comments and recommendations for consideration in the design and construction of the proposed pipeline crossings under the QEW. This report does not address the environmental aspects of the project.

Limitations associated with this report and its contents are provided in the statement included in Appendix A.

2.0 SITE DESCRIPTION AND GEOLOGY

2.1 SITE LOCATION

The locations of the proposed crossings are shown on the Borehole Location Plan provided in Appendix B. For the purpose of this report the alignment of Credit River has been taken as east-west and the QEW as north-south.



The Stantec Oil and Gas group prepared Crossing Plan and Profile Drawings (Drawing No. 160950937PL-PLD0003 & 160950937PL-PLD0004, dated November 13, 2018) for the proposed HDD installations of both pipeline crossings of the QEW. The drawings are included in Appendix B for reference.

2.2 SITE DESCRIPTION

At the location of the crossing, the QEW is a six-lane divided freeway (with 3 lanes in each direction) with exit and entry lanes on both directions connecting the QEW to Mississauga Road.

The QEW is approximately 33 m wide, with 3 m wide shoulders on both sides. There is a guard rail on the west side of the freeway and a noise barrier on both sides.

The traffic surface of the freeway is at an approximate elevation of 94.5 m and 95.4 m above mean sea level (AMSL).

2.3 SUBSURFACE LITERATURE REVIEW

The following information sources were reviewed:

• The Physiography of Southern Ontario, by Chapman and Putnam (2007);

• The Quaternary Geology of Ontario, Southern Sheet, Map 2556, by Ministry of Northern Development and Mines (1991);

• Ontario Geological Survey (OGS) 2010, Surficial Geology of Southern Ontario;

• Ontario Geological Survey (OGS) 2007, Paleozoic Geology Map of Southern Ontario;

• Ontario Ministry of Northern Development and Mines Geotechnical Boreholes / Ontario Geological Survey (OGS) online database;

• Ontario Ministry of Transportation (MTO) GEOCRES Number: 30M12-324: Foundation Investigation and Design Report Construction Access Road for Bridge Rehabilitation QEW Bridge over Credit River, Mississauga, Ontario (2011);

The Physiography of Southern Ontario indicates that the project area is in the region known as the Iroquois Plain which, in the immediate area, consists of relatively thin native soil deposits overlying bedrock. This can be further described as Glaciolacustrine deposits overlying Paleozoic Bedrock of the Georgian Bay Formation, in reference to the Quaternary Geology of Southern Ontario Map 2556 and the OGS Paleozoic Geology Map of Southern Ontario. Glaciolacustrine deposits generally consist of sand, gravelly sand and gravel (beach and nearshore deposits) and the bedrock in Georgian Bay Formation is typically made up of shale and limestone.

The Surficial Geology of Southern Ontario describes the glaciolacustrine deposits in this area as course textured sand, gravel, minor silt and clay, and Foreshore and basin deposits. Credit River and its adjacent floodplains indicate a surficial geology of Modern alluvial deposits which consists of clay, silt, sand and gravel. These soils may contain organic remains.



The review of the OGS online database yielded one (1) borehole near the HDD exit point. The borehole location was on the QEW southbound shoulder approximately 25 meters north of the HDD exit point. The borehole (Reference ID 853581) was completed in 1997 and was terminated at 4.6 m below existing grade. The surface elevation was recorded as 96.7 m AMSL. The subsurface conditions encountered were described as topsoil (0 m to 0.3 m); till, silt, clayey, sand, grey, stiff (0.3 m to 2.1 m); and shale, limestone, dolomite (2.1 m to 4.6 m).

The review of the MTO GEOCRES database yielded one report for a location to the north of the exit point. Seven (7) boreholes were drilled in the floodplain and tableland south of Credit River along, and adjacent to, what is now the MTO access road. Boreholes 10-01, 10-02, and 10-05 were drilled between approximately 103 m and 179 m north of the HDD exit point and boreholes 10-03, 10-03A, 10-03B and 10-04 were drilled on the Credit River floodplain underneath the QEW, approximately 222 m to 244 m north of the proposed HDD alignment. Borehole 10-01 was located approximately 103 m north of the proposed HDD exit point; borehole 10-05 was located approximately 40 m north of borehole 10-01; borehole 10-02 was located approximately 37 m north of borehole 10-05; and borehole 10-04 was located in the floodplain south of the Credit River. In general, the conditions consisted of thin overburden (ranging from 0.6 m to 3.7 m) underlain by shale bedrock. The overburden was classified generally as topsoil/fill; underlain by clayey silt (within the floodplain); underlain by silty clay.

The clayey silt in the flood plain had a thickness ranging from 0.8 m to 3.7 m bottom of this stratum at an elevation ranging between 72.6 m and 75.7 m AMSL. Standard Penetration Test (SPT) ‘N’ values from 8 to 26 indicated a stiff to very stiff consistency. The moisture content in the clayey silt ranged from 10% to 55%. Grain size analyses conducted on several samples from this layer indicated 0% to 3% gravel, 23% to 44% sand, 36% to 59% silt, and 15% to 22% clay. One (1) representative Atterberg Limits test had a plasticity index of 15% and liquid limit of 33%, indicating a low plasticity cohesive soil (CL). Two (2) of the boreholes (10-03A and 10-03B) drilled on the floodplain underneath the QEW had a layer of peat 0.6 m to 1.0 m thick, the bottom of the peat being at elevations of 72.6 m to 73.2 m AMSL. The peat had a firm consistency (as indicated by 4 to 7 blows per 0.3 m penetration) and moisture contents ranging from 55% to 87%.

The silty clay in the tableland (boreholes 10-01, 10-02 and 10-05) was directly below the topsoil and ranged from 0.6 m to 3.2 m below the existing ground surface which corresponds to approximate elevations of 95.6 m and 91.2 m AMSL. SPT ‘N’ values from 12 to 39 indicated a stiff to hard consistency. The moisture content in the silty clay ranged from 11% to 23%. Grain size analyses conducted on several samples from this layer indicated 0% to 10% gravel, 5% to 59% sand, 22% to 47% silt, and 16% to 58% clay. Atterberg Limits tests had plasticity indices ranging from 15% to 24%, with liquid limits of 37% to 55%, indicating an intermediate to high plasticity cohesive soil (CI or CH).

The following table, extracted from the GEOCRES report, provides a summary of the depths and elevations of the weathered shale encountered at the borehole locations.



Table 2.1: Summary of GEOCRES Depths and Elevations of Weathered Shale

Borehole Number

Depth to Weathered Shale (m)

Top of Weathered Shale Elevation (m AMSL)

Comments

10-011 0.6 95.6 N/A

10-021 3.2 91.2 N/A

10-03A 3.7 72.6 In floodplain

10-03B 3.7 72.6 In floodplain

10-04 3.5 72.8 In floodplain

10-051 1.4 93.9 N/A 1 Proved by coring below augered depth

The shale bedrock encountered was typical of the Georgian Bay Formation. The shale was highly to moderately weathered within the upper 2 m and moderately to slightly weathered below this depth. Limestone beds were identified within the shale, and ranged from 25 mm to 100 mm thick, with occasional layers up to 150 mm thick. Occasional clay seams were also observed in the shale bedrock.

The coring of the shale bedrock provided the following:

• Total Core Recovery (TCR) generally between 95% and 100%

• Rock Quality Designation (RQD) generally between 80% and 100% indicating typically fair to good rock quality. Lower RQD values, roughly 30%, were recorded in the upper weathered zones (first core run) in several boreholes

• Fracture Index (FI) generally 0 to 5 fractures per 0.3 m of core with occasional values between 10 and 20.

• Discontinuities and bedding planes largely horizontal with occasional sub-vertical joints.

The results of point load tests carried out on select samples of the rock cores were used to provide an indication of the Unconfined Compressive Strengths (UCS) of the shale. The values inferred ranged from less than 1 MPa to roughly 13 MPa. The strength of the hard limestone interbeds ranged from 28 MPa to 200 MPa, with the intermediary shaley limestone bedrock ranging from 2 MPa to 48 MPa.

Boreholes 10-01 and 10-02 included monitoring well installations; a single well in 10-01 and a nested well (two wells screened at different depths) in 10-01. These two boreholes, as previously indicated, are near the HDD alignment (< 10 m) south of Credit River. Borehole 10-01 is approximately 50 m north of the entry point. Borehole 10-02 is approximately 77 m north of borehole 10-01 and therefore closer to the Credit River. The monitoring well at borehole 10-01 was sealed into the bedrock and readings after stabilization were recorded as 9.3 m (October 12, 2010) and 10 m (December 17, 2010) below existing ground surface. Corresponding



elevations are 86.9 m ABSL and 86.2 m AMSL, respectively. One monitoring well in borehole 10-02 was sealed at the soil-shale interface; the well yielded no recordable water table six (6) weeks after installation. The second monitoring well in borehole 10-02 was sealed in the shale; the water level was 8.7 m below existing grade on October 12, 2010 and 9.3 m below existing grade on December 17, 2010. Corresponding elevations are 85.7 m ABSL and 85.1 m AMSL, respectively. It should be noted that groundwater conditions fluctuate seasonally and due to changing weather conditions, and this data may not be representative of groundwater conditions today.

3.0 PROPOSED CROSSINGS

3.1 HDD ALIGNMENT AND PROFILE

It is intended to install the proposed NPS 10 and NPS 20 pipelines on parallel alignments approximately 3 m apart.

The crossings will have entry points approximately 365 m south of the centerline of the Credit River and approximately 70 m and 76 m west of the QEW. The crossings will have exit points approximately 317 m and 310 m south of the centerline of the Credit River and approximately 48 m east of the QEW. Location of the exit and entry pits are shown on the Location Plan inset to the Crossing Plan and Profile Drawings (Drawing No. 160950937PL-PLD0005 & 160950937PL-PLD0006) provided in Appendix A.

The total drill length of the HDD crossings will be approximately 103.6 m and 103.5 m for the NPS 10 and NPS 20 pipelines respectively.

The Profile for the NPS 10 pipeline indicates that the lowest portion of the HDD will be at approximately elevation 87 m AMSL which is approximately 10.4 m below the highway surface shown at approximately elevation 97.4 m AMSL.

The Profile for the NPS 20 pipeline indicates that the top of pipe at the lowest point of the HDD will be at approximately elevation 88.5 m AMSL which is approximately 8.8 m below the highway surface shown at approximately elevation 97.3 m AMSL.

3.2 TEMPORARY WORK SPACE

There are two (2) temporary work spaces (TWSs) proposed. One is located adjacent the entry point and covers an area of approximately 15 m x 13.8 m. The other is located and covers an area of approximately 24 m x 12 m. The TWS near the entry point will lie between the QEW to the east and a residential neighborhood to the west. The TWS near the exit point will be in proximity to an access road to the west of the QEW and to the immediate east of a residential neighborhood.



3.3 EXISTING STRUCTURES

There are several buried utilities below the travelled surface of the QEW in proximity to the entry and exit points. There are two buried 300 mm sewer lines, a 900 mm sewer line and a 1050 mm sewer line all crossing the proposed HDD alignment. The vertical clearance between the HDD alignments and the sewer lines varies with a minimum clearance of 1.5 m shown on the Crossing Plan and Profile Drawings. The drawings are included in Appendix B for reference.

There are also noise barrier walls and several overhead wires located on both sides of the highway and a hydro one corridor located on the west side of the highway.

4.0 SCOPE OF WORK

The scope of work developed for the geotechnical investigation was as follows:

• Advance four (4) boreholes at the locations shown on the plan in Appendix B and described as follows:

o One (1) borehole (BH1A) near the location of the entry point;

o One (1) borehole (BH2A) near the location of the exit point;

o One (1) borehole (BH1) drilled on the east side of the QEW;

o And one (1) borehole (BH7) between the north and south bound lanes (between Boreholes BH1A and BH2A) of the QEW.

• Advance the boreholes to a depth consistent with terminating approximately 5 m

below the invert of the proposed pipeline alignment unless conditions encountered warrant shallower termination.

• Core bedrock (where encountered and/or where auger refusal is encountered in the

boreholes) using HQ-size (63.5 mm diameter core) rock coring equipment in accordance with the procedures outlined in ASTM D2113 “Standard Practice for Rock Core Drilling and Sampling of Rock for Site Exploration” and ASTM D6032 “Standard Test Method for Determining Rock Quality Designation (RQD) of Rock Core.”

• Record the soil/bedrock conditions encountered in the boreholes.

• Document groundwater conditions if and where observed in the open boreholes at

the time of the drilling program and immediately prior to backfilling the boreholes.

• Install a monitoring well in Borehole BH1A to measure the static groundwater level.



• Return to the site following completion of the drilling and installation of the monitoring well and vibrating wire piezometer (after time allowed for piezometer saturation and groundwater stabilization in monitoring well) to record the groundwater level.

• Supplement the field information with a geotechnical laboratory testing program to

provide geotechnical characterization of the soils encountered.

On completion of the field investigation and laboratory testing program, it was intended to collate the relevant information, and prepare a geotechnical report with appropriate descriptions of the existing soil, bedrock and groundwater conditions at the crossing location, with implications for the proposed HDDs. For reference, Boreholes BH1 and BH2 were drilled for a slightly different alignment proposed previously for the pipeline crossings of the QEW, and BH3 to BH6 were drilled for the Credit River and Lynchmere Avenue crossings and are reported under separate covers. The revised alignment for the QEW crossing warranted the addition of Boreholes BH1A, BH2A and BH7 (located on the QEW).

5.0 METHOD OF INVESTIGATION

5.1 FIELD INVESTIGATION

Prior to commencing the field investigation, Stantec contacted Ontario One Call to locate underground public utilities to provide utility clearances. In addition, Stantec retained the services of a utility locate company, OnSite Locates, to provide private utility locate services to identify any traceable underground utilities at or in proximity to the borehole locations.

Permission to access the borehole location adjacent to the south/west bound and north/east bound lanes of the QEW (Boreholes BH7 & BH1) for the purpose of conducting the geotechnical investigation was obtained in the form of a, ‘Highway Corridor Management Encroachment Permit’, issued to Stantec by the MTO. Traffic control, in accordance with Ontario Traffic Manual Book 7 Temporary Condition, was provided by On Track Safety Ltd. (OTS).

Stakeholder and landowner consent(s) and access for the borehole drilling program were obtained by Stantec prior to accessing the borehole locations.

The borehole drilled west of QEW near the entry point was labelled as borehole BH1A, the borehole drilled east of the Queen Elizabeth Way near the exit point was labelled as borehole BH2A, and the borehole drilled near the center barrier on the QEW between the north/east bound and south/west bound lanes was labelled as borehole BH7. The borehole drilled approximately 53 m north of Borehole BH7, on the shoulder of the north/east bound lane of the QEW, was labelled as BH1. The borehole locations are shown in Appendix B.

The boreholes labelled BH2 to BH6 were drilled for the Credit River and Lynchmere Avenue crossings and are referenced under separate covers.



The fieldwork component of the geotechnical investigation was carried out on November 20, 2017 and June 24, 26 and 27, 2018.

The boreholes were advanced using a track mounted CME 55 drill rig equipped with hollow-stem augers (HSA). Stantec field personnel recorded the conditions encountered in the boreholes. Soil samples were recovered at regular intervals using a 50-mm (outside diameter) split-tube sampler by conducting Standard Penetration Tests (SPTs) in accordance with the procedures outlined in ASTM specification D1586.

All soil samples recovered from the boreholes were placed in moisture-proof bags and returned to Stantec’s laboratory for geotechnical classification with a number of samples selected for geotechnical laboratory testing.

Bedrock coring was conducted in HQ size (63.5 mm diameter core) in accordance with the procedures outlined in ASTM specification D2113. For each run, the Total Core Recovery (TCR), Solid Core Recovery (SCR), and Rock Quality Designation (RQD) were recorded (Explanations of these characteristics are provided on the Symbols and Terms Sheets in Appendix C). The rock was placed in core boxes, labeled and transported to our offices for visual inspection and laboratory testing on select samples.

Groundwater levels could not be obtained in the open boreholes due to the introduction of water for bedrock coring.

A monitoring well was installed in Borehole BH1A. The monitoring well consisted of a 50 mm diameter PVC pipe with a 3 m long slotted pipped section screened within the shale bedrock. The well was backfilled with bentonite hole plug to approximately 0.4 m below the bottom of the pipe, then silica sand to 0.3 m above the top of the screen, and then bentonite hole plug installed to ground surface. The monitoring well installation details are provided on the Borehole Record for BH1A in Appendix C.

The remaining boreholes were backfilled with a mixture of cement and bentonite.

5.2 SURVEYING

The borehole locations were established in the field with reference to the existing site features with consideration for drilling constraints and limitations, such as the presence of nearby underground utilities.

On completion of the drilling, the borehole locations were surveyed by Stantec Geomatics. The approximate locations of the boreholes, including the Modified Transverse Mercator (MTM) NAD 83 northing and easting coordinates and respective ground surface elevations referenced to a geodetic datum are provided in Table 5.2 below. The horizontal coordinates are considered accurate to less than 0.5 m and the elevations are considered accurate to less than 0.1 m.



The coordinates and ground surface elevations are also shown on the borehole records in Appendix C.

Table 5.1: Borehole Location and Ground Surface Elevations

Borehole No. MTM Coordinates (NAD83 - Zone 10) Ground Surface Elevation

(m) N E

BH1 4823874 295905 95.9

BH1A 4823759 295807 97.5

BH2A 4823806 295718 97.8

BH7 4823778 295751 97.5

5.3 LABORATORY TESITNG

All samples obtained from the four (4) boreholes were subjected to visual and tactile examination on return to the geotechnical and construction materials testing laboratory.

Based on a review of the field borehole records and visual and textural examination of the samples obtained, the following laboratory testing program was implemented.

Soil

• Grain size distribution with hydrometer 4 samples • Atterberg Limits tests 4 samples • Natural Moisture Content All samples

Bedrock • Unconfined Compressive Strength (UCS) Tests 20 samples • Unit Weight tests 20 samples

The results of the laboratory tests are discussed in the text of this report and are provided on the Borehole Records in Appendix C. Figures illustrating the results of the grain size distribution tests and Atterberg Limits tests are included in Appendix D.

Unless specific instructions are received to the contrary, the samples will be discarded three months after issue of this report.



6.0 SUBSURFACE CONDITIONS

6.1 FRAME OF REFERENCE

6.1.1 Overburden

The soils encountered in the boreholes and reported herein have been classified in accordance with the Unified Soil Classification System as defined in ASTM D2487 with modifications consistent with the methods of the Ministry of Transportation of Ontario (MTO). The modifications specifically include the removal of the descriptions “lean” and “fat” with reference to clay soils and include a “Medium” category with respect to plasticity.

It should be noted that the internal diameter (I.D.) of the SPT sampler is 38 mm and hence the grain size test results and soil classifications may not reflect the entire gravel size fraction which extends to 75 mm diameter. If the presence of cobbles (particles from 75 mm to 300 mm) and boulders (particles > 300 mm) are inferred to be present, they will be described separately from the gravel content.

6.1.2 Bedrock

The Ontario Ministry of Transportation and Communication Document RR229, Evaluation of Shale for Construction Projects, includes a typical weathering profile of the low durability shale that prevails across the region. The Georgian Bay shale falls into this category. The weathering profile was reproduced from Skempton, Davis, and Chandler. The profile differentiates the shale into three grades of weathering and four zones as described below in Table 6.1.

Table 6.1: Typical Weathering Profile of Low Durability Shale

Zone Description Notes

Fully Weathered IVb soil like matrix only indistinguishable from glacial drift deposits, slightly clayey, may be fissured

Partially Weathered

Iva soil like matrix with occasional pellets of shale less than 3 mm diameter

little or no trace of rock structure, although matrix may contain relic fissures

III soil like matrix with frequent angular shale particles up to 25 mm diameter

moisture content of matrix greater than the shale particles

II

angular blocks of un-weathered shale with virtually no matrix separated by weaker chemically weathered but intact shale

spheroidal chemical weathering of shale pieces emanating from relic joints and fissures, and bedding planes

Unweathered I Shale regular fissuring



6.2 OVERVIEW

The borehole locations are shown on Figure 1 included in Appendix B.

The subsurface conditions observed in the boreholes are presented in detail on the Borehole Records provided in Appendix C. An explanation of the symbols and terms used to describe the Borehole Record is also provided in Appendix C.

In general, the overburden stratigraphy encountered in the four (4) boreholes consisted of:

• Topsoil (BH1A, BH2 & BH2A) or asphalt (BH7) over fill; underlain by, • Native silty sand (BH1A & BH2A); underlain by, • Clay (BH2A) or clay with gravel (BH2); underlain by, • Completely to highly weathered shale and limestone; underlain by, • Slightly to moderately weathered shale.

Bedrock of the Georgian Bay formation was encountered underlying the overburden in all boreholes, at depths of between 1.5 m to 2.9 m below grade, or at elevations of between 96.3 and 94.6 m AMSL.

The introduction of water into boreholes during drilling precluded observation of free groundwater conditions in the open boreholes on completion of drilling. The groundwater level was subsequently recorded on July 31, 2018 within the monitoring well installed in Borehole BH1A and on December 18, 2017 from the VWP installed at borehole BH2 and was approximately 4.6 m below existing grade (Corresponding to approximate elevation 92.9 m) and 6.0 m below existing grade (corresponding to approximate elevation of 90.9 m) respectively.

6.3 OVERBURDEN

6.3.1 Topsoil

Topsoil 50 mm and 300 mm thick was encountered at boreholes BH1A and BH2A respectively.

6.3.2 Granular Fill

Granular fill consisting of sand and gravel was encountered below the asphalt in Borehole BH1 and extended to a depth of 0.9 m below grade, corresponding to elevation 95.0 m.

Granular fill consisting of silty sand was encountered below the asphalt in Borehole BH7 and extended to a depth of 2.9 m below grade, corresponding to elevation of 94.6 m. The fill contained concrete fragments near the top of the layer and inferred cobbles and boulders from auger grinding throughout the layer.

The N-values obtained from the SPTs advanced through the granular fill ranged from 27 to 50 blows per 76 mm. Based on the N-values, consistency of this soil was assessed as compact to hard.



The samples of the soil recovered from the granular fill were assessed as moist to wet based on visual and textural examination of the samples in the field. Laboratory tests yielded moisture contents ranging from approximately 0.9% to 18.6%.

Grain size distribution test was completed on one (1) sample from these soils. The results of the test are shown in Table 6.2 below:

Table 6.2: Grain Size Distribution – Silty Sand (SM) Fill

Borehole Sample Depth (m)

Description % Gravel % Sand % Silt % Clay

BH7 SS2 1.1 SILTY SAND (SM) 0 71 8 21

The results of the grain size distribution test are shown on the Borehole Record Sheets included in Appendix C and are illustrated on Figure 1 in Appendix D.

In accordance with the Unified Soil Classification System, the samples tested can be classified as Silty Sand (SM) fill.

6.3.3 Silty Clayey Sand with Gravel (SC-SM) to Silty Sand (SM)

Silty sand was encountered below the topsoil in Borehole BH1A and BH2A and extended to a depth of 1.8 and 1.1 m (corresponding to elevation of 95.7 and 96.7 m) respectively.

A silty clayey sand with gravel layer was encountered below the granular fill in Borehole BH1 and extended to a depth of 2.4 m, corresponding to elevation of 93.5 m.

The N-values obtained from the SPTs advanced through the silty clayey sand with gravel to silty sand layer ranged from 6 to 14 blows per 305 mm penetration. Based on the N-values, consistency of this soil was assessed as loose to compact.

The samples of the soil recovered from the silty sand were assessed as moist to wet based on visual and textural examination of the samples in the field. Laboratory tests yielded moisture contents ranging from approximately 8.0% to 24.2%.

Grain size distribution tests were completed on two (2) samples from these soils. The results of these tests are shown in Table 6.3 below:

Table 6.3: Grain Size Distribution – Silty Clayey Sand to Silty Sand (SM)



BH1 SS3 1.8 SILTY CLAYEY SAND with GRAVEL (SC-SM)

26 46 21 7

BH1A SS2 1.1 SILTY SAND (SM) 1 60 27 12



The results of the grain size distribution tests are shown on the Borehole Record Sheets included in Appendix C and are illustrated on Figure 1 in Appendix D.

An Atterberg Limits test was completed on the above samples and the results are shown in Table 6.4 below.

Table 6.4: Atterberg Limits Tests Results –Clay to Clay with Gravel


Description Liquid Limit Plastic Limit Plasticity Index

BH1 SS3 1.8 SILTY CLAYEY SAND with GRAVEL (SC-SM)

22 17 5

BH1A SS2 1.1 SILTY SAND (SM) NP NP NP

The results of the Atterberg Limits Tests are shown on the Borehole Record sheets included in Appendix C and are illustrated on Figure 2 in Appendix D.

In accordance with the Unified Soil Classification System, the samples tested can be classified as Silty Clayey Sand (SC-SM) to Silty Sand (SM).

6.3.4 CLAY (CL)

A layer of brown to mottled grey clay was encountered below the silty sand in borehole BH2A, which extended to 1.5 m below grade, corresponding to elevation 96.3 m.

An N-value of 7 was obtained from the SPT advanced through the. Based on this, consistency of this soil was assessed as firm.

The samples of the soil recovered from the clay layer was assessed as dry to moist based on visual and textural examination of the samples in the field. Laboratory tests yielded moisture contents of approximately 17.8%.

A grain size distribution test was completed on one (1) sample from these soils. The results of this test are shown in Table 6.5 below:

Table 6.5: Grain Size Distribution – Clay (CL)



BH2A SS2 1.2 CLAY (CL) 6 8 40 46

The results of the grain size distribution test are shown on the Borehole Record Sheets included in Appendix C and are illustrated on Figure 1 in Appendix D.

An Atterberg Limits test was completed on the above sample and the results are shown in Table 6.6 below.



Table 6.6: Atterberg Limits Tests Results – Clay (CL)


Description Liquid Limit Plastic Limit Plasticity Index

BH2A SS2 1.2 CLAY (CL) 44 19 25

The results of the Atterberg Limits Tests are shown on the Borehole Record sheets included in Appendix C and are illustrated on Figure 2 in Appendix D.

In accordance with the Unified Soil Classification System, the samples tested can be classified as Clay (CL).

6.4 BEDROCK

6.4.1 Inferred Bedrock

The lower portion of the stratigraphy augered in each of the boreholes was inferred to consist of highly to completely weathered shale bedrock (Georgian Bay Formation) based on the limited penetration (virtual refusal) of the SPT, samples recovered, and consideration of the conditions encountered underlying this zone. The depth to the contact surface with the inferred highly to completely weathered shale bedrock (and respective geodetic elevation) is shown in Table 6.7 below.

Table 6.7: Inferred Highly to Completely Weathered Shale Bedrock

Borehole Depth (m)

Geodetic Elevation (m)

Thickness (m)

BH1 1.5 96.3 2.1

BH1A 1.8 95.7 1.7

BH2A 1.5 96.3 2.1

BH2 1.5 95.4 2.0

BH7 2.9 94.6 >0.6

Consistent with the frame of reference provided in a preceding section, the inferred bedrock would be considered representative of Zone IVb exhibiting a soil like matrix.

6.4.2 Bedrock Core

Coring of the bedrock was conducted in all the boreholes. The bedrock cored consisted of grey shale with limestone interbedding. It was interpreted that the bedrock was from the Georgian Bay Formation.

Photographs of the bedrock cores obtained during the investigation is included in Appendix E for reference.



The bedrock formation encountered, depths of the coring and corresponding elevations, and total core recovery (TCR), solid core recovery (SCR) and rock quality designation (RQD) are shown in Table 6.8 below.

Table 6.8: Summary of Bedrock Coring Operations

Borehole No.

Rock (Georgian Bay Formation)

Depth (mbgs)

Geodetic Elevation

(m)

TCR (%)

SCR (%)

RQD (%)

BH1 Grey shale with occasional limestone interbeds, slightly weathered

5.7 - 14.0 81.9-90.2 77 - 100 60 - 98 0 - 81

BH1A Grey shale with occasional limestone interbeds, moderately weathered

3.0 – 14.1 83.4 - 94.6 70 - 100 48 to 99 0 to 82

BH2A Grey shale with occasional limestone interbedding, moderately weathered

3.1 – 14.1 83.7 – 94.8 88 - 100 41 - 99 0 - 81

BH2 Grey shale with limestone interbedding, slightly to moderately weathered

3.5 – 13.7 83.2 – 93.4 85 - 100 70 - 100 16 - 78

BH7 Grey shale and limestone, highly weathered 2.9 – 3.5 94.0-94.6 67-100 0-38 0

Based on the RQD range indicated in the table, the bedrock core obtained from Borehole BH1 is classified as very poor to good in quality. The bulk of the rock core in this borehole was characterized as slightly weathered.

Based on the RQD range indicated in the table, the bedrock core obtained from Borehole BH1A is classified as very poor to good in quality. The bulk of the rock core in this borehole was characterized as moderately weathered.

Based on the RQD range indicated in the table, the bedrock core obtained from Borehole BH2A is classified as very poor to good in quality. The bulk of the rock core in this borehole was characterized as moderately weathered.

Based on the RQD range indicated in the table, the bedrock core obtained from Borehole BH7 is classified as very poor quality. The bulk of the rock core in this borehole was characterized as highly weathered.

Twenty (20) samples of the rock core obtained from the boreholes were selected for testing to determine the Unconfined Compressive Strength (UCS). The results of the tests are shown in Table 6.9 below.



Table 6.9: Results of Unconfined Compressive Strength (UCS) on Samples of Rock Core

Borehole No.

Median Depth (m bgs)

Median Geodetic Elevation

(m)

Unit Weight (kg/m3)

UCS (MPa) Notes

BH1 8.7 87.2 2609 10.5

BH1A

4.0 93.5 2619 61.0 2 Note 1

7.0 90.5 2607 3.1

9.1 88.4 2557 4.4

9.3 88.2 2558 6.6

10.1 87.4 2539 4.2

11.5 86.0 2443 2.5

12.1 85.4 2569 6.8 Note 1

14.0 83.4 2543 3.5

BH2A

5.0 92.8 2564 2.6 Note 1

5.8 92.0 2630 3.7

6.9 90.9 2557 5.0

7.2 90.6 2595 4.6

9.4 88.4 2764 2.5

10.4 82.4 2594 6.0 Note 1

10.6 87.2 2602 3.1

11.9 85.9 2602 2.8

12.3 85.5 2515 3.8

13.0 84.8 2592 2.5 Note 1

14.0 83.8 2655 2.7 Notes:

1 The rock core specimen tested had a dimeter to length ratios (L/D) of slightly less than 1.80 (e.g. 1.39 to 1.74). The UCS results were subsequently corrected using the method used for concrete cylinder testing as specified in CAN-CSA.

2 Sample tested was limestone. The UCS test results indicate that the shale is a very weak to weak rock (reference Table 3.5 Classification of Rock with Respect to Strength, in the Canadian Foundation Engineering Manual). A single UCS test result indicated that the limestone interbed is a strong rock (reference the table in the Canadian Foundation Engineering Manual referenced in the preceding paragraph).



6.4.3 Bedrock Properties

A summary of the typical physical properties of the Georgian Bay Formation bedrock was provided in the Ontario Ministry of Transportation and Communication publication RR229 – Evaluation of Shales for Construction Projects - An Ontario Shale Rating System, dated March 1983. Extracts of the physical properties are presented below in Table 6.10 for reference.

Table 6.10: Typical Physical Properties for the Georgian Bay Formation

UCS Young's Modulus Poisson's Ratio

(MPa) (GPa)

Average 28 4 0.19

Range 8 to 41 0.5 to 12 0.10 to 0.25

A comparison of the UCS test results with the values provided in Table 6.10 above indicates that the shale bedrock encountered in the boreholes for the current investigation is weaker than would be considered typical.

In southern Ontario, all rock formations including the Georgian Bay Formation are known to possess “locked-in or residual” horizontal stresses. The magnitude of these stresses varies with depth but the literature reports a maximum in the order of 25 MPa (Lo, 1987). Specific measurements of the horizontal stresses were not included as a component of this investigation.

The Georgian Bay Formation is also known to have a tendency to swell on exposure and immersion. Measurement of the swelling potential was not included as a component of this investigation. A review of literature references indicates that for the Georgian Bay Formation the swelling potential in the horizontal plane could be in the range of 0.01% to 0.43% per log cycle of time and the swelling potential in the vertical plane could be in the range of 0.2% to 1.4% per log cycle of time. These ranges indicate the anisotropy associated with the formation and the differences to be expected in the vertical and horizontal directions.

As observed in the core obtained from the boreholes, limestone beds are present in the Georgian Bay formation shale. The literature indicates that the stronger limestone, siltstone and sandstone beds are typically less than 100 mm thick although layers up to 600 mm thick have been reported. The literature also reports the presence of thin hard limestone beds which, when closely-spaced, can collectively be 1 m thick.

Laboratory testing to determine the tensile strength of the bedrock was not included as a component of this investigation. Literature references indicate a range in tensile strength of 0.5 MPa to 11.1 MPa for the shale bedrock of the Georgian Bay Formations. One reference indicated that the tensile strength of the shale could be approximated as 5% to 10% of the unconfined compressive strength.



6.5 GROUNDWATER

Water was used for the rock coring and as a result, observations of the presence of free groundwater in the open boreholes could not be obtained on completion of drilling the boreholes.

A monitoring well was installed in borehole BH1A screened within the slightly to moderately weathered shale with occasional limestone interbeds. On July 31, 2018 the static groundwater level was recorded at approximately 4.6 m below existing grade or at an elevation of 92.9 m AMSL.

7.0 MISCELLANEOUS

The field work was carried out under the supervision of Rebecca Borysenko, Field Technician, under the direction of Adam Hatch, P. Eng.

The drill rig was supplied and operated by Geo-Environmental Drilling Inc.

Geotechnical laboratory testing was carried out at Stantec’s Markham laboratory.

This report was prepared by Shanti Ratmono, M.Eng., E.I.T. and Katurah Firdawsi, P. Eng.

This geotechnical report was reviewed by John J. Brisbois, MScE, P. Eng., MTO Designated MTO Principal Foundation Contact.

8.0 CLOSURE

A subsurface investigation is a limited sampling of a site. The subsurface conditions described herein are based on information obtained at specific borehole locations. Conditions between and beyond the borehole locations must be expected to vary beyond that described herein.

Should any conditions be encountered at the site that differ from the conditions encountered at the borehole locations as described herein, we request that we be notified immediately to assess the additional information and revise the content and recommendations in this report, as warranted.



GEOTECHNICAL INVESTIGATION REPORT Proposed Pipeline Installation – Crossing of the Queen Elizabeth Way (QEW)

Mississauga, Ontario

9.0 DISCUSSION

9.1 PROJECT DESCRIPTION AND BACKGROUND

9.1.1 Overall Project

The Ontario Ministry of Transportation (MTO) has requested that two (2) of Trans Northern Pipeline Inc.’s (TNPI) pipelines (NPS 10 and 20 inch) be relocated at the Credit River crossing to allow for the twinning of the Queen Elizabeth Way (QEW) bridge across Credit River. The project will require the installation of two (2) new pipelines by way of four trenchless crossings, NPS 10 and NPS 20 under the QEW and NPS 10 and 20 under the Credit River.

Stantec Consulting Ltd. (Stantec) was retained by TNPI to complete a geotechnical investigation for the pipeline crossings. The investigation is required to determine the subsurface conditions at the crossing locations to assess the technical feasibility and to support the design of the crossings. This geotechnical report is specific to the QEW crossings. A geotechnical report for the Credit River crossings is presented under a separate cover.

The proposed pipelines will cross the existing infrastructure (Queen Elizabeth Way) along the alignment. The crossing is intended to be undertaken using Horizontal Directional Drilling (HDD).

9.1.2 Queen Elizabeth Way Crossing

9.1.2.1 Alignment

This investigation report is focused on the required crossing of Queen Elizabeth Way.

Horizontal Directional Drilling (HDD) is the proposed method of construction at this crossing.

The Crossing Plan and Profile drawings used in the preparation of this geotechnical report illustrated the preliminary horizontal and vertical alignments of the NPS10 and NPS 20 at the crossing location. Plan and Profile drawings were prepared by the design engineer, dated November 13, 2018. The drawings are included in Appendix B for reference.

The drawings indicated that the installation will consist of a heavy wall NPS 10 (10 inch/254 millimeter outside diameter) with a wall thickness of 9.3 mm, and an NPS 20 (20 inch/508 millimeter outside diameter) pipe with a wall thickness of 10.3 mm. The pipe is specified as CSA Z245.1-18, CAT II M45C with a design pressure of 9,930 kPa.



The drawings indicated that the QEW will be widened and its alignment will be shifted towards west at the crossing location. However, it is understood that the proposed HDD installation will be carried out prior to the road widening/shifting and the new alignment.

The Plan and Profile drawings indicate that the entry pit on the east side to have a width in the order of 12.0 m and a length in the order of 24.0 m, and extend approximately 7.0 m below existing ground surface, and the exit pit on the west side to have a width in the order of 13.8 m and a length in the order of 15.0 m, and extend approximately 7.0 m below existing ground surface. Based on the Plan and Profile drawing and the bore pit layout provided, the key dimensions and elevations of the proposed pipe installation with respect to the existing QEW are as follows:

• Bore Length (inferred from the crossing plan and profile) ~103.6 m (NPS 10) ~103.5 m (NPS 20)

• Bottom of Excavation – east side of Queen Elizabeth Way 89.4 m • Lowest Top of Pipe Elevation – NPS 20 88.3 m • Lowest Top of Pipe Elevation – NPS 10 86.9 m • Bottom of Excavation – west side of Queen Elizabeth Way 90.1 - 90.4 m • Ground Surface Elevation – east side of Queen Elizabeth Way 97 m • Road Surface Elevation – East Bound QEW centerline 96.4 m • Road Surface Elevation – West Bound QEW centerline 96.6 m • Ground Surface Elevation – west side of Queen Elizabeth Way 97.7 m

Based on the depths and elevations referenced above:

• The top of pipes will be approximately 8.8 m and 10.4 m below the road surface and 8.3 m and 9.1 m below the ditches of the existing QEW.

• The bottom of the east and west pits will be in the order of 7.0 m and 6.4 m below existing grade, translating to elevations of approximately 89.4 m, and 90.1 m to 90.4, respectively.

The drawings indicated the presence of several underground services and utilities at the crossing location. The deepest utility/service shown is a ‘drain sewer line’ with obvert elevation 90 m and clearances of 1.5 m and 3.0 m from the proposed alignments of NPS 20 and NPS 10, respectively.

9.1.2.2 MTO Complexity Rating for Tunneling Specialty Services

With reference to the Guidelines For Foundation Engineering – Tunneling Specialty For Corridor Encroachment Permit Application issued by the MTO, a pipe diameter ≤ 1 m with minimum overburden > 3 X the pipe diameter beneath a major Freeway translates to a Complexity Rating for Tunneling Specialty Services (Table 1 in the Guidelines) of Medium.



9.1.2.3 Construction Staging & Detours

In the area of the crossing location, the Queen Elizabeth Way consists of a 6-lane paved road (3 lanes in each direction). The road has steel guard rails and noise barrier walls along both sides of the highway.

Given the inferred locations of the entry and exit pits there is no anticipation for disruption to traffic flow on the QEW as a direct result of the construction activities. However, there may be temporary constraints to traffic flow during set-up/take-down of equipment and during the execution of the settlement monitoring program that is typically required by MTO during construction.

10.0 TRENCHLESS TECHNOLOGY INSTALLATION

10.1 OVERVIEW OF TRENCHLESS TECHNOLOGY METHODS

The intended installation method at the proposed crossing is horizontal directional drilling (HDD). For reference, an overview of conventional trenchless methods is provided herein. Taking into consideration the soil and groundwater conditions referenced herein, the diameter of the product pipe, length of the trenchless installation and depth of the installation the four (4) methodologies outlined on Table 10.1 below were considered. Given the relatively small pipe diameters (i.e. NPS 10 and NPS 20) the microtunneling method was not considered. Based on the advantages and disadvantages outlined, each of the methodologies has been ranked.

The advantages, disadvantages and comparative ranking of the options are summarized in Table 8.1 below.

Table 10.1: Comparison of Trenchless Technology Options

Installation Methods Advantages Disadvantages Ranking

Horizontal Directional

Drilling (HDD)

• Suitable for variety of ground conditions above and below groundwater table.

• Drive lengths up to about 180 m (small diameter) to 2000 m (large diameter)

• Supports pipe internal diameter of 500-1500 mm

• Steerable both horizontally and vertically; accuracy about 1% of length

• Installation can be done in pits to reduce installation length

• Large setback required for surface-to-surface installation

• Risk of ground loss, sinkhole and settlement for installation in overburden

• Large workspace required for drilling equipment and pullback section

1



Installation Methods Advantages Disadvantages Ranking

Horizontal Directional

Boring (HDB)

• Suitable for short and long installations for a variety of soil conditions similar to HDD

• Deep entry/exit pits required for deep installations

• Risk of ground loss, sinkhole and settlement as only minimal hydrostatic mud pressure can be provided for installation in overburden

• Boulders and concentration of cobbles can impede or deflect the bore path

2

Track Bore • Relatively simple installation procedure

• Bore is fully supported during installation

• Can be fast • Supports pipe internal diameter

of 150-900 mm • Some control of direction;

accuracy about 50 mm for relatively short installations

• Deep entry/exit pits required for deep installations

• Length of the proposed installation is near the upper limit of typical auger boring operation (up to about ~100 m)

• Installation difficulty in rock (shale with limestone beds)

• Potential for ground loss and settlement in cohesionless soils below groundwater table

• Boulders larger than 1/3 bore diameter can impede the bore path and deflect the bore

3

Pipe Ramming • Relatively simple installation procedure

• Bore is fully supported during installation

• Can be fast • Supports pipe internal diameter

of 50-1200 mm

• Pipe ramming in bedrock is not feasible

• Length of the proposed installation is beyond the limit of typical pipe ramming operation (up to about 75 m)

• Boulders can deflect the pipe path during ramming leading to a lower accuracy of installation

• Can cause significant heave • Can cause damage to the

pipe coating during installation • Vibration can cause impact on

surrounding infrastructure • No directional control

(not feasible in rock)

Based on the advantages and disadvantages summarized in Table 8.1, the use of HDD is considered the ‘preferred’ construction method for the installation of the pipeline.



10.2 HORIZONTAL DIRECTIONAL DRILLING

10.2.1 Overview

It is understood that Horizontal Directional Drilling (HDD) from an entry pit to an exit pit is the preferred method for the pipeline installations at this crossing.

The HDD process as presented in the literature reference Guidelines for Preventing Underground Facility Damage as a Result of Horizontal Direction Drilling, developed by J.D. Hair and Associates, dated March 2012 is comprised of a three-stage process; pilot hole, pre-reaming, and pullback as described below. For additional reference, a section describing the use of drilling mud is provided.

10.2.1.1 Pilot Hole

The pilot hole begins when the bit enters the ground at the entry point located directly in front of the rig. As the bit is advanced away from the rig, individual joints of drill pipe are added behind it in succession creating a continuous string of drill pipe in the hole.

In soft soils, progress is typically achieved using a high-velocity stream of drilling mud to erode the soil ahead of the bit. This is referred to as jetting. In harder soils and rock, mechanical cutting action is required. This is provided by a hydraulically driven mud motor which allows for continuous rotation of the bit.

As the pilot hole is drilled, its actual path is monitored using either a transmitter or a steering tool positioned as close as possible to the bit. Directional control is achieved using a non-rotating drill string with an asymmetrical leading edge. The asymmetry of the leading edge creates a steering bias while the non-rotating aspect of the drill string allows the steering bias to be held in a specific position while drilling. If a change in direction is required, the drill string is rolled so the direction of bias is the same as the desired change in direction. The drill string may also be continuously rotated where directional control is not required. On large rig installations, leading edge asymmetry is typically accomplished with a bent sub or a bent motor housing located directly behind the bit. Leading edge asymmetry on small rig installations is typically accomplished using a slant-faced bit.

Pilot-hole drilling continues until the bit punches out at the exit point on the opposite end of the crossing, at which point the pilot hole is complete.

10.2.1.2 Pre-Reaming

Enlargement of the pilot hole is typically accomplished by conducting one or more pre-reaming passes until the desired hole size has been achieved. The number of passes that are required is dependent upon the diameter of the pipeline being installed and the properties of the subsurface materials along the drilled path.



For a typical pre-reaming pass, a reaming tool is attached to the drill string at the exit point and is rotated and drawn back to the drill rig, thus enlarging the hole. This process has the benefit of maintaining tension on the reamer throughout the reaming operations. Drill pipe is typically added behind the reamer as it progresses toward the rig so that a full string of pipe is maintained in the hole throughout the process.

It is also possible to ream away from the drilling rig. This is referred to as “push reaming” whereby the reamer is fitted into the drill string and rotated and advanced away from the drill rig using only the drill rig’s thrust. However, push reaming is generally considered to be poor practice as it increases the potential for a drill pipe failure.

10.2.1.3 Drilling Mud

Typically, a drilling mud is injected into the bore during the cutting and reaming process to stabilize the hole and remove soil cuttings.

The drilling mud typically consists of a clay or polymer material; the most common clay used is a sodium montmorillonite (referred to as bentonite). The drilling mud must have sufficient gel strength to keep the cuttings suspended for transport, to form a filter cake on the boring wall that contains the water within the drilling mud, and to provide lubrication between the pipe and the boring wall on pullback.

The drilling mud used are often described as thixotropic and thus thicken when left undisturbed after pullback. However, unless cementitious agents are added, the thickened mud provides little to no side-support for the pipe.

10.2.1.4 Pullback

Prior to commencing pullback operations, the pipeline to be installed is typically assembled to its full length on the side of the crossing opposite the drilling rig. This prefabricated segment is referred to as the pull section. Once the hole has been enlarged to its final diameter, the pipeline is installed in the reamed hole by attaching the pull section behind a reaming assembly at the exit point, then pulling both the reaming assembly and pull section through the hole to the drilling rig.

A swivel is placed between the pull section and the reaming assembly to minimize the amount of torsion that is transmitted to the pipeline being installed.

The pull section is typically supported as it proceeds into the hole using some combination of roller stands and pipe handling equipment to minimize the tensile load and prevent damage to the pipeline.



11.0 DESIGN CONSIDERARTIONS

11.1 ANTICIPATED STRATIGRAPHY ALONG THE HDD PATH FOR CONSTRUCTION

The table below summarizes the anticipated stratigraphy to be encountered along the HDD alignments for the NPS 10 and NPS 20 crossings respectfully.

Borehole1

Approximate Elevation of HDD Alignment at Borehole Location 2

(m) Strata Anticipated along the Proposed HDD Alignment 3

NPS 10 NPS 20

BH1A 90.2 90.4 Very Poor to Fair Quality Shale with Limestone interbeds

BH7 86.8 88.3 Inferred Shale with Limestone interbeds 4

BH2A 90.8 90.8 Fair Quality Shale with Limestone interbeds Notes:

1 The order of the boreholes as shown is arranged from the entry point on the east to the exit point on the west.

2 The alignment referenced in the table was shown on the HDD Plan and Profile provided for use in the preparation of this geotechnical report.

3 The conditions noted were extracted from the respective borehole records. It is noted that the conditions between and beyond the borehole locations and deeper than the termination depth of the boreholes must be expected to vary beyond that described.

4 Borehole was terminated at elevation 94.0 m (above HDD alignment) in weathered shale.

The bulk of the HDD installation is anticipated to be below the prevailing groundwater level. The groundwater level is taken as 4.6 m below grade (Elevation 92.9 m AMSL).

11.2 FEASIBILITY OF HDD CONSTRUCTION

The following bullets provide a brief overview of the feasibility of the HDD approach for this crossing.

• The work requires a crossing of the MTO Right-of-Way (QEW). Open cut excavation in the MTO Right-of-Way is not permitted, necessitating the adoption of a trenchless technology approach.

• The construction methodology associated with HDD will serve to mitigate potential disruption to traffic flow on QEW.

• There is no existing MTO infrastructure in immediate proximity to the crossing location. • The proposed length of the HDD path (~100 m) is within the limit of the length typically

considered in the industry for HDD for a 10” and 20” pipe diameters.



• The crossing location has sufficient space for the placement of entry/exit pits at the locations intended.

• Based on the conditions encountered in the boreholes encountered the entire HDD paths will be in the bedrock of Georgian Bay Formation consisting of shale with limestone.

• The base of the entry/exit pits is anticipated to be below the inferred groundwater level. A low rate of water infiltration should be anticipated in the entry/exit pits from the fine-grained overburden soils encountered in the boreholes at these locations. However, as the entry/exit pits may encounter the highly to moderately weathered shale and limestone, a moderate rate of water infiltration is possible as groundwater typically is present at the contact surface between the overburden and the bedrock.

• The HDD installation will be below the measured groundwater level.

Based on the statements provided above, the HDD method of construction is considered a feasible method of construction for this crossing.

11.3 CONTRAINTS AND LIMITATIONS OF HDD

The following constraints and limitations are set forth for consideration by the designer for the use of HDD for this crossing:

Entry and Exit Pits

• To protect existing utilities/services from damage, it is anticipated that any/all existing utilities/services will be located and marked in the field prior to commencement of construction. Of particular note are any existing utilities and services in the immediate areas of the entry and exit points where the HDD and the existing utilities and services may be at a similar depth. Exposure of utilities/services to provide visual confirmation of location and depth to confirm that adequate separation is maintained for protection during the HDD operation should be considered.

• The excavations for the HDD entry/exit pits are anticipated to be 6.4 m to 7.0 m deep. On the east side of the QEW, it is anticipated that excavations to a depth of 7.0 m will

encounter loose to compact silty sand over weathered shale and limestone bedrock to shale bedrock.

On the west side of the QEW, it is anticipated that excavations to a depth of 6.4 m will encounter loose silty sand underlain by firm clay underlain by weathered shale and limestone bedrock to shale bedrock.

Groundwater was encountered at a depth of 4.6 m (Elevation 92.9 m AMSL) in BH1A and a depth of 6.0 m (Elevation 89.9 m AMSL) in BH2.

• The depths referenced in the preceding bullet indicate that excavation of soil and bedrock will be required.

• The excavation of the entry and exit pits must consider the prevailing soil, bedrock and groundwater conditions, particularly with respect to stability of open cut excavations. It is anticipated that temporary construction shoring will be required for the excavation of the entry and exit pits.



• The entry and exit pits must be kept reasonably dry to permit construction operation to proceed. Given the groundwater levels referenced, de-watering is anticipated to be required. Seepage will occur from the overlying silty sand and fractures/fissures/jointing in the shale bedrock.

HDD Alignments

• The bedrock present along the profiles is anticipated to consist of very poor quality to good quality shale with limestone interbedding to shale. Where there are layers in the shale and limestone beds are present, steering difficulties can be encountered where the drill ‘bounces’ off a more competent or stronger rock layer. The presence of fractures in the rock can also influence the steering. The design and construction of HDD should consider the presence of strong limestone interbeds within the very weak to weak shale.

• At shallow depth along the drill path, an inadvertent loss or return of drilling fluids can occur via an “open pathway” such as may be provided by fracturing/jointing in the shale, particularly in the surficial/shallow weathered zone. Spikes in the annular operating pressure associated with temporary blockage or collapse of the HDD drill hole can force open apertures in the shale, exacerbating this condition.

• At increasing depth, the risk of an inadvertent loss or return of drilling fluids becomes less (though still exists), given the increasing mass of overlying rock, and the potential presence of layers/interbeds of stronger rock including the limestone.

• The Georgian Bay Formation is known to possess high in situ horizontal stresses and time dependent swelling potential. The resulting phenomenon is often referred to as “rock squeeze” and can adversely impact infrastructure installed in the rock. The typical over-drill used for HDD installation (e.g. hole diameter ~50% larger than pipe) should be sufficient to address any rock squeeze that may occur.

• Based on the conditions encountered in the boreholes, the HDD drill path will penetrate below the static groundwater table. For design purposes it is recommend that the groundwater level be taken as approximate elevation 92.9 m AMSL.

• There is only a horizontal clearance of approximately 3 m and a vertical clearance of approximately 1.5 m (for lower portion of HDD path) between the proposed alignments for NPS 10 and NPS 20. The design and construction of the HDD should minimize pilot hole tolerances to mitigate potential for disturbance of the pipeline that is installed first.

Considering the ground surface topography along the length of the HDD alignments as shown on the Site Profiles referenced, there is no obvious indication of concerns with respect to potential slope instability for the proposed pipeline. Table 11.1 provides a summary of the potential risks, key issues associated with the risks, mitigation strategies and risk levels.



Table 11.1: Risk Register for HDD Installation and Possible Impact to Infrastructure

Risk Item Key Issues Mitigation Strategy Unmitigated Risk Level

Mitigated Risk Level

HDD Installation Drill Bit Skipping

The drill bit can skip at the contact between the overburden (and/or completely weathered shale) and the contact with the bedrock resulting in deviation from the planned alignment.

• Use of entry/exit pits and HDD installation in bedrock.

• Reduce the length of the drill path via pits.

M L

Inadvertent Return of Drilling Mud

Inadvertent release of drilling fluid to the ground surface may occur at shallow depths due to reduced lithostatic pressure. Possible in the overburden or shallow weathered zone of bedrock, but unlikely.

• Installation in bedrock.

L

L

Rock Squeeze

High in-situ horizontal stresses and time dependent swelling can adversely impact the pipeline installation.

• Over-drilling (typically used in HDD). M

L

Steering Difficulties

Potential soil seams and limestone in bedrock at shallow depths may cause steering difficulties causing the HDD to deviate from the planned alignment.

• Establish HDD alignment at a sufficient depth to avoid the majority of the seams.

M L

Possible Impact on Infrastructure MTO QEW As the HDD is installed in the

bedrock, it is unlikely to have any impact on the road.

None. L L

Utilities and Services

Utilities/services (two 300-mm, one 900-mm, and one 1050-mm sewer lines).

• Utilities/services must be located to confirm adequate separation is maintained.

• Limit pilot hole tolerances

• Pilot hole alignment tracking

M L

11.4 TUNNELMAN’S GROUND CLASSIFICATION & POTENTIAL SETTLEMENT

Although the majority of the HDD will be within the shale and limestone bedrock, Table 11.2 is provided for completeness and as general information. This table provides the framework for Tunnelman’s Ground Classification and indicates the respective tunnel working conditions for reference.



Table 11.2 Tunnelman’s Ground Classification and Probable Working Conditions

Soil Classification Representative Soil Types Tunnel Working Conditions

Hard Very hard calcareous clay; cemented sand and gravel

Tunnel heading may be advanced without roof support

Firm Loess above GWT; Various calcareous clay with low plasticity

Tunnel heading may be advanced without roof support and the permanent support can be constructed before the ground will start to move

Slow Raveling and Fast Raveling

Fast Raveling occurs in residual soils or in sand with clay binder below the GWT. Above the GWT, the same soils may be Slowly Raveling or even Firm

Chunks or flakes of material begin to drop out of roof or the sides sometime after the ground has been exposed.

In Fast Raveling ground, the process starts within a few minutes; otherwise it is classed as Slow Raveling

Squeezing Soft or medium-soft clay

Ground slowly advances into tunnel without fracturing and without perceptible increase of water content in ground surrounding the tunnel (may not be noticed in tunnel but cause surface subsidence)

Swelling

Heavily pre-compressed clays with a plasticity index in excess of about 30; Sedimentary formations containing layers of anhydrite.

Like squeezing ground, moves slowly into tunnel, but the movements are associated with a very considerable volume increase in the ground surrounding the tunnel.

Cohesive Running and Running

Cohesive running occurs in clean, fine moist sand

Running occurs in clean, coarse or medium sand above the GWT

The removal of the lateral support of any surface rising at an angle of more than about 34° to the horizontal is followed by a ‘run,’ whereby the material flows like granulated sugar until the slope angle becomes equal to about 34°. If the ‘run’ is preceded by a brief period of raveling, the ground is called Cohesive Running

Very Soft Squeezing Clays and silts with high plasticity index

Ground advances rapidly into the tunnel in a plastic flow

Flowing Any ground below the GWT that has an effective grain size in excess of about 0.005 mm

Flowing ground moves like a viscous liquid. It can invade the tunnel not only through the roof and the sides but also through the bottom. If the flow is not stopped, it continues until the tunnel is completely filled.

Bouldery

Boulder glacial till; rip-rap fill; some land slide deposits, some residual soils. The matrix between boulders may be gravel, sand, silt, clay or combinations of thereof.

Problems occurred in advancing shield or in forepoling; blasting or hand mining ahead of machine may become necessary.



With respect to potential settlement at the level of the travel surface on QEW, the following comments, conditions, and assumptions apply:

• There will be drilling mud in the bore throughout the construction process; • There is a thickness of approximately 6 m to 8 m of bedrock above the HDD bore path at the

location of QEW.

Based on the comments, conditions and assumptions outlined above, the potential for deformation, distortion, or settlement to occur on the travel surface of QEW is considered to be negligible and should not exceed the Review Limit of 10 mm as stated in MTO’s Guidelines For Foundation Engineering – Tunneling Specialty For Corridor Encroachment Permit Application.

11.5 RECOMMENDATIONS

11.5.1 Non-Standard Special Provision

A copy of the “Pipe Installation by Trenchless Method, Non-Standard Special Provision (NSSP), dated December 2014 is included in Appendix F for reference.

The NSSP includes the general requirements relating to the installation of pipes by trenchless methods. The attached copy has not been revised to reflect the proposed scope of construction as described herein.

The NSSP as attached is intended to:

• Indicate the MTO’s expectations to the designers of what is required to be addressed and included in the designer; and,

• To understand the benchmark upon which the contract documents will be reviewed by the MTO from a geotechnical perspective.

The contractor should prepare and provide a comprehensive HDD execution plan addressing the requirements of the NSSP and the following, in advance of undertaking the work.

• HDD entry/exit pit installation, dewatering and surface water management; • Navigation and monitoring of the HDD; • Directional drilling procedures including addressing the presence and/or removal of

obstacles if encountered; • HDD continuance and or contingency plans; and, • Pullback operations including addition of other pullback sections and resumption or

suspension of pullback operations (for welding, or if stuck).

11.5.2 Monitoring

The MTO Guidelines for Foundation Engineering – Tunneling Specialty For Corridor Encroachment Permit Application includes an appendix titled “Settlement Monitoring Guidelines – Tunneling”. The appendix addresses the requirements for a settlement monitoring program to prevent damage to existing utilities and highway structures along the tunnel alignment.



Section 7.06 titled Instrumentation Monitoring in the NSSP referenced in the preceding section also addresses the requirements for a settlement monitoring program.

In general, the monitoring program provides for:

• completion of a pre-condition survey of the existing pavement; • installation of surface settlement markers and deep settlement monitoring points; • collection of settlement monitoring data; • assessment of the settlement monitoring data with comparison to prescribed trigger levels;

and, • distribution of results of the monitoring including notification if the trigger level(s) are

exceeded with recommended corrective and/or preventive measures as warranted if movements are recorded.

11.6 GEOTECHNICAL PARAMETERS FOR HDD ANALYSIS

The required geotechnical parameters for the analysis of the HDD were developed using empirical methods based on a number of literature references and standards including the Canadian Foundation Engineering Manual (4th Edition, 2006) and Foundation Analysis and Design (Bowles et al, 5th Edition, 1997).

The table below includes values for the geotechnical parameters, specific to the subsurface stratigraphy encountered in BH2 to BH4 advanced for the three crossings.

Table 11.3 Geotechnical Parameters for HDD Analysis

Soil Type Total Unit Weight

ɣ (kN/m3)

Effective Cohesion

c’ (kPa)

Effective Internal Angle of

Friction Ø’ (°)

Undrained Shear

Strength Su (kPa)

Shear Modulus

G (MPa)

Poisson’s Ratio ν

Firm to very stiff clay with gravel

20 0 28 50 10 0.45

Loose to compact silty sand

21 0 31 N/A 10 0.35

Completely weathered shale

23 15 33 N/A 100 0.35

Very poor quality shale 25.5 50 33 N/A 500 0.25

Poor or better quality shale

26 100 40 N/A 1500 0.2

Parameters provided for the bedrock (equivalent cohesion and equivalent friction angle) are based on the Hoek-Brown Failure Criterion for a rock mass for tunneling design purposes. Reference can be made to section 9.3 above, for comments regarding the potential for “rock squeeze” which can adversely impact infrastructure installed in the rock.



Consistent with the comments in section 11.3 above, the Georgian Bay Formation is known to possess high in situ horizontal stresses and time dependent swelling potential. The resulting phenomenon is often referred to as “rock squeeze” and can adversely impact infrastructure installed in the rock. The over-drilling typically used to facilitate HDD installation is anticipated to be sufficient to address any rock squeeze that may occur.

The total overburden pressure, Po can be calculated using the total unit weights provided in the table. The effective overburden pressure, Po’ may be calculated as Po minus the hydrostatic pressure calculated based on the ground water level.

The groundwater level should be taken at elevation 92.9 m AMSL consistent with the monitoring well reading in BH1A on July 31, 2018.

12.0 CONSTRUCTION CONSIDERATIONS

12.1 EXCAVATIONS AND DEWATERING

Excavations must be conducted in accordance with the requirements of the Occupational Health & Safety Act & Regulations (OH&S Act) for Construction Projects. For the purpose of this report, we have presumed that the temporary excavations for the entry/exit pits could be open for a period of approximately two weeks.

The native firm to very stiff clay with gravel and loose to compact silty sand can be classified as Type 3 soils. The side slopes in unsupported excavations in Type 3 materials must not be steeper than 1:1 (Horizontal: Vertical) in accordance with the OH&S Act.

The bedrock encountered in the boreholes typically consisted of very poor quality rock (RQD < 25%) in the surficial highly to completely weathered zone transitioning to good quality rock (RQD from 75% to 90%) with increasing depth.

Excavation in the overburden should be relatively straight forward using medium to large hydraulic excavators.

Excavation in the surficial highly to completely weathered zone should be possible using similar equipment. With increasing depth and where limestone layers are present, hoe ramming with pneumatic rock breakers will be required.

Materials should not be stockpiled in proximity to the open excavations. Construction traffic should not be permitted in proximity to the open excavations. To protect against the adverse effects of erosion, all ground surface runoff should be directed away from the area of the excavations.

If space is restricted such that the side slopes of the excavations for the entry and exit pits cannot be safely cut back in accordance with the OH&S Act regulation, sloughing and cave-in



are encountered in the excavations, or where the excavation is in close proximity to a road, building or infrastructure, temporary shoring must be provided.

To prevent overstressing of the shoring structure, the excavated spoil should be placed away from the edge of the excavation at a distance equal to 2 times the depth of the excavation.

Side slopes of temporary excavations in the bedrock may be left near vertical. Consistent with the OH&S Act, the walls of an excavation in rock should be stripped of any loose rock or other material that could slide, fall, or roll upon a worker. Regular inspections by qualified geotechnical engineering personnel should be conducted for any excavation in the bedrock to confirm that conditions are safe and consistent with the requirements of the OH&S Act. Side slopes in the surficial highly to completely weathered zone should be consistent with a Type 1 soil consistent with the OH&S Act.

The groundwater level was recorded at a depth of 4.6 to 6.0 m below grade via the VWP installed in BH2 and the monitoring well installed in BH1A. The volume of infiltration/seepage into the excavations (approximately 6.4 to 7.0 m deep) in the area of the HDD entry and exit pits is anticipated to be moderate. The use of sump pits and contractor’s pumps should be adequate in handling the seepage and infiltration incurred.

With the depth of the excavations, a more extensive dewatering system and effort may be required. The design of the dewatering system would need to address the extent of dewatering required, the depth of intended excavation, and the soil and groundwater conditions that prevail at the intended excavation location. An evaluation of possible consequences of more extensive dewatering should be conducted in advance of construction.

Any dewatering program should contain a communication protocol with the regulatory agencies and the public, short term containment, sampling and analysis, permitting, disposal, and reporting requirements.

The preceding comments are intended for general reference and information only. The Contractor is solely responsible for the design and implementation of any required unwatering and/or dewatering, including requirements for withdrawal, handling, treatment, and discharge.

Consistent with the current Ontario Ministry of the Environment and Climate Change regulations, an Environmental Activity and Sector Registry (EASR) is required for dewatering over 50,000 L/day and a Permit to Take Water (PTTW) is required for dewatering in excess of 400,000 L/day.

12.2 TEMPORARY SHORING

As previously mentioned, a temporary shoring system may be required for the entry/exit pits at the site.

The recommended parameters for consideration in the design of a temporary shoring system are provided in Table 12.1 below. Specific elevations for each of the strata specific to the borehole locations can be obtained for the borehole records in Appendix C.



Table 12.1: Soil Parameters for Design of Temporary Shoring System

Soil Ko (at rest)1

Ka (active)1

Kp (passive)1

Undrained Shear Strength

(kPa)

Effective Friction Angle φ` (°)

Bulk Unit Weight ϒb

(kN/m3)

Firm to very stiff clay with gravel 0.53 0.36 2.77 50 28 20

Loose to compact silty sand 0.48 0.32 3.12 N/A 31 21

Note: 1 The coefficients of lateral earth pressures provided are for a level ground surface adjacent the

limits of the excavation/shoring system. The parameters should be adjusted if a sloping ground surface exists or if surcharges are applied.

The undrained shear strength and friction angles provided in the table have been developed based on the soil conditions encountered in the boreholes as documented herein and consideration of literature references for similar soils. Project-specific field or laboratory testing has not been undertaken as a component of this investigation to confirm the values presented.

For purposes of design of the temporary shoring system, it is recommended that the groundwater elevation be taken as 4.6 m below grade (elevation 92.9 m AMSL).

The design of the temporary shoring system should be conducted by a Professional Engineer licensed to practice in the Province of Ontario.

The design of the temporary shoring system should conform to OPSS 539, Performance Level 2.

The temporary shoring system should be designed in accordance with the methods described in the Canadian Foundation Engineering Manual, 2006 Edition (CFEM). Loading conditions (e.g. triangle/apparent) appropriate for the type of the shoring system selected (e.g. rigid/flexible and with/without anchorage/struts) as discussed in Section 26.10 of CFEM must be considered in the analysis and design of the temporary shoring system. It is recommended that effective parameters be used in the lateral load calculation as a more conservative approach than the use of undrained parameters.

The stability of the base of the excavation should be evaluated in accordance with Sections 22.3 and 26.11 of the CFEM as a component of the design of the temporary shoring system.

Reference is given to OPSS 539 which pertains to excavation support and protection systems.

The contractor is responsible for the completed detailed design of the temporary shoring system.



12.3 REMOVAL OF PROTECTIVE SYSTEMS AND BACKFILLING

Temporary shoring installed within the MTO property for any aspect of the project must be removed in a safe manner on completion of construction.

Reference is given to OPSS 539 which pertains to excavation support and protection systems.

On removal of temporary shoring, the excavations must be backfilled. The excavations and any adjacent disturbed areas should be restored to an equivalent (or better) condition than existed prior to the commencement of construction.

12.4 BEDDING AND BACKFILL

Pipe bedding materials specifications for the pipeline, if required at the locations of the tie-in or launch pits should be in accordance with the manufacturer’s and/or the designer’s recommendations.

The proposed bedding material should be assessed at the time of construction and will largely be dependent on the stability of the base of the excavation and the groundwater conditions encountered at the time of construction. Granular materials would typically be acceptable for this purpose. The use of clear or crushed stone and a geosynthetic wrap can be considered if there is standing water in the excavations at the time of placing the pipeline.

Trench or excavation backfill can consist of the excavated native soils subject to inspection and approval at the time of construction to confirm suitability for reuse. Topsoil, organics, debris, and similar materials should not be considered for reuse as backfill.

Should imported materials be required for trench backfill, consideration could be given to the use of OPSS Select Subgrade Material (SSM) for this purpose. If groundwater is present in the excavations, then consideration to the use of granular backfill materials will be required, such as OPSS Granular B Type II or suitable and pre-approved crushed rock fill. Fill materials imported to the project site must meet all applicable municipal, provincial, and federal guidelines and requirements associated with environmental characterization of the materials.

In settlement sensitive areas the backfill (approved materials) should be placed in maximum 200 mm thick loose lifts and compacted to a minimum of 95% of the materials SPMDD.

In non-settlement sensitive areas, the backfill may consist of the approved portions of the excavated soils placed in 300 mm thick lifts and compacted to a minimum of 92% SPMDD to the finished sub-grade level.

12.5 ESTIMATES OF HYDRAULIC CONDUCTIVITY

For reference, the results of the grain size distribution tests (and Unified Soil Classifications) completed on the predominant soil strata encountered in the boreholes has been compared to the grain size curves and soil types referenced in Supplementary Standard SB-6 of the 2006



Ontario Building Code (OBC). The OBC has been used as a guideline to estimate the likely range in the coefficient of permeability of the soils encountered in the investigation. It is noted that the industry typically refers to “hydraulic conductivity” rather than “coefficient of permeability” in this respect. The terms are often considered interchangeable, but for purposes of this report the values provided are in the form of “length/time” (cm/sec) and are therefore considered strictly applicable to “hydraulic conductivity”, and hence “hydraulic conductivity” is used herein.

Based on the comparison conducted, the following values are provided:

• Silty Sand (SM) 10-3 – 10-5 cm/sec • Clay to Clay with gravel (CL) 10-6 cm/sec or less • Shale 10-5 cm/sec or less

The OBC states, in part, that “it must be emphasized that, particularly for fine grained soils, there is no consistent relationship (between coefficient of permeability and soils of various types) due to the many factors involved”. Such factors as structure, mineralogy, density (compactness or consistency), plasticity, and organic content of the soil can have a large influence on the hydraulic conductivity; variations in excess of an “order of magnitude” are common place in this respect.

The hydraulic conductivity of the shale bedrock is anticipated to be typically less than 10-5 cm/sec; however, it is variable and subject to the rock quality and distribution of fractures and joints/beddings in the rock mass.

GEOTECHNICAL INVESTIGATION REPORT

A

APPENDIX A Statement of General Conditions

SEPTEMBER 2013

STATEMENT OF GENERAL CONDITIONS USE OF THIS REPORT: This report has been prepared for the sole benefit of the Client or its agent and may not be used by any third party without the express written consent of Stantec Consulting Ltd. and the Client. Any use which a third party makes of this report is the responsibility of such third party. BASIS OF THE REPORT: The information, opinions, and/or recommendations made in this report are in accordance with Stantec Consulting Ltd.’s present understanding of the site specific project as described by the Client. The applicability of these is restricted to the site conditions encountered at the time of the investigation or study. If the proposed site specific project differs or is modified from what is described in this report or if the site conditions are altered, this report is no longer valid unless Stantec Consulting Ltd. is requested by the Client to review and revise the report to reflect the differing or modified project specifics and/or the altered site conditions. STANDARD OF CARE: Preparation of this report, and all associated work, was carried out in accordance with the normally accepted standard of care in the state or province of execution for the specific professional service provided to the Client. No other warranty is made. INTERPRETATION OF SITE CONDITIONS: Soil, rock, or other material descriptions, and statements regarding their condition, made in this report are based on site conditions encountered by Stantec Consulting Ltd. at the time of the work and at the specific testing and/or sampling locations. Classifications and statements of condition have been made in accordance with normally accepted practices which are judgmental in nature; no specific description should be considered exact, but rather reflective of the anticipated material behavior. Extrapolation of in situ conditions can only be made to some limited extent beyond the sampling or test points. The extent depends on variability of the soil, rock and groundwater conditions as influenced by geological processes, construction activity, and site use. VARYING OR UNEXPECTED CONDITIONS: Should any site or subsurface conditions be encountered that are different from those described in this report or encountered at the test locations, Stantec Consulting Ltd. must be notified immediately to assess if the varying or unexpected conditions are substantial and if reassessments of the report conclusions or recommendations are required. Stantec Consulting Ltd. will not be responsible to any party for damages incurred as a result of failing to notify Stantec Consulting Ltd. that differing site or sub-surface conditions are present upon becoming aware of such conditions. PLANNING, DESIGN, OR CONSTRUCTION: Development or design plans and specifications should be reviewed by Stantec Consulting Ltd., sufficiently ahead of initiating the next project stage (property acquisition, tender, construction, etc), to confirm that this report completely addresses the elaborated project specifics and that the contents of this report have been properly interpreted. Specialty quality assurance services (field observations and testing) during construction are a necessary part of the evaluation of sub-subsurface conditions and site preparation works. Site work relating to the recommendations included in this report should only be carried out in the presence of a qualified geotechnical engineer; Stantec Consulting Ltd. cannot be responsible for site work carried out without being present.

GEOTECHNICAL INVESTIGATION REPORT

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APPENDIX B Drawings

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Disclaimer: Stantec assumes no responsibility for data supplied in electronic format. The recipient accepts full responsibility for verifying the accuracy and completeness of the data. The recipient releases Stantec, its officers, employees, consultants and agents, from any and all claims arising in any way from the content or provision of the data.

160950937 REVA

0 10 20metres

1:750 (At Original document size of 11x17)

Prepared by BCC on 2018-12-18

Borehole Location Plan

1. Coordinate System: NAD 1983 UTM Zone 17N2. Base features produced under license with the Ontario Ministry ofNatural Resources and Forestry © Queen's Printer for Ontario, 2016.3. Orthoimagery © First Base Solutions, 2016. Imagery Date, unknown.

TRANS-NORTHERN PIPELINES INC.CREDIT RIVER AND QEW CROSSING VIA HDD

Legend"́ Borehole (2017)

"

³ Vibrating WirePiezometer (2017)

"¡ Borehole (2018)

"́ Borehole withMonitoring Well (2018)Proposed PipelineTNPI Pipeline (Existing)

! ! Hydro LineMunicipal Boundary -Lower Tier

Regional Municipality OfPeel

Project Location

Client/Project

Appendix

Title

J.J. BRISBOIS

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Geotechnical Investigation Report

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