June 2022 G-14642.71-006-R-Rev0_FINAL iv Table of Contents 1.0 INTRODUCTION......................................................................................................................................................................................... 1 1.1 Project Outline .........................................................................................................................................................................................1 1.2 Project Elements Assessed as Part of this Report .....................................................................................................1 1.3 Scope of Work ..........................................................................................................................................................................................1 1.4 Site Visits.......................................................................................................................................................................................................2 1.5 Co-ordinate System and Units of Measure.....................................................................................................................2 2.0 RELIANCE ON OTHER EXPERTS .................................................................................................................................................. 3 3.0 PROPERTY DESCRIPTION AND LOCATION ......................................................................................................................... 3 4.0 SETTING.......................................................................................................................................................................................................... 5 4.1 Geology......................................................................................................................................................................................................... 5 4.2 Geomorphology .....................................................................................................................................................................................7 4.3 Groundwater.............................................................................................................................................................................................7 4.4 In-situ Stress Conditions .................................................................................................................................................................7 5.0 ACCESS TUNNEL OVERVIEW .......................................................................................................................................................10 6.0 WILLOWS ROAD ACCESS TUNNEL AND VENT SHAFT 1 ........................................................................................... 12 6.1 Geotechnical Investigations ......................................................................................................................................................12 6.1.1 Field mapping .................................................................................................................................................................................12 6.1.2 Boreholes .............................................................................................................................................................................................12 6.1.3 Laboratory testing.........................................................................................................................................................................13 6.1.4 Summary of geotechnical characteristics of Willows Road farm.......................................................15 6.2 Tunnel Portal ..........................................................................................................................................................................................15 6.2.1 Ground conditions .......................................................................................................................................................................15 6.2.2 Groundwater.................................................................................................................................................................................... 16 6.2.3 Key geotechnical issues ......................................................................................................................................................... 16 6.3 Ventilation Shaft 1.............................................................................................................................................................................. 16 6.3.1 Ground conditions .......................................................................................................................................................................17 6.3.2 Discontinuity characteristics .............................................................................................................................................. 19 6.3.3 Groundwater...................................................................................................................................................................................20 6.3.4 Key geotechnical issues ..........................................................................................................................................................21 6.4 Tunnelling Issues ................................................................................................................................................................................22
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