APPENDIX 3.0-E Feasibility Geotechnical Pit Slope Evaluation Kitsault Project British Columbia ...

141 Pages·2011·5.31 MB·English

KITSAULT MINE PROJECT
ENVIRONMENTAL ASSESSMENT
APPENDICES

APPENDIX 3.0-E
Feasibility Geotechnical Pit Slope
Evaluation Kitsault Project British
Columbia, Canada

VE51988 – Appendices

AVANTI KITSAULT MINE LTD
KITSAULT MOLYBDENUM PROJECT
FEASIBILITY STUDY REPORT
C.1 FEASIBILITY GEOTECHNICAL PIT SLOPE
EVALUATION SRK NOV 2010
Project No. 165003 APPENDIX C – 1
January 2011
Feasibility Geotechnical Pit Slope
Evaluation
Kitsault Project
British Columbia, Canada

Report Prepared for
Avanti Mining Inc.

Report Prepared by

November 2010
Feasibility Geotechnical Pit Slope Evaluation
Kitsault Project
British Columbia, Canada

Avanti Mining Inc.
5251 DTC Parkway
Suite 405
Greenwood Village, CO
80111

SRK Consulting (U.S.), Inc.
Suite 3000, 7175 West Jefferson Avenue
Denver, Colorado, USA 80235
Tel: [phone]
Fax: [phone]
E-mail: [email protected]
Web site: www.srk.com

SRK Project Number 2CA020.004

November 2010

Author
Michael Levy, P.E., P.G.
SRK Consulting
Feasibility Geotechnical Pit Slope Evaluation, Kitsault Project Page i

Table of Contents
1  Introduction and Background ................................................................................. 1 
2  Program Objectives and Work Program ................................................................ 3 
2.1  Program Objectives ........................................................................................................ 3 
2.2  Work Program ................................................................................................................ 3 
3  Geologic Setting ...................................................................................................... 4 
3.1  Local Geology ................................................................................................................ 4 
3.2  Major Geologic Structures .............................................................................................. 4 
4  Field Data Collection ............................................................................................... 6 
4.1  Geotechnical Core Logging ............................................................................................ 6 
4.1.1  Geotechnical Logging Procedures ............................................................................... 7 
4.1.2  Core Drilling Method ..................................................................................................... 7 
4.2  Discontinuity Orientation ................................................................................................ 8 
4.3  Point Load Testing ......................................................................................................... 8 
4.4  Geotechnical Observations of Existing Pit ..................................................................... 9 
4.5  Packer Testing ............................................................................................................... 9 
5  Laboratory Testing ................................................................................................ 11 
5.1  Unconfined Compressive Strength and Elastic Properties ........................................... 11 
5.2  Triaxial Compressive Strength Testing ........................................................................ 13 
5.3  Direct Shear Testing..................................................................................................... 13 
5.4  Direct Tensile Strength Testing .................................................................................... 15 
5.5  Unit Weight Measurements .......................................................................................... 15 
6  Geotechnical Model ............................................................................................... 16 
6.1  Data Analysis ............................................................................................................... 16 
6.1.1  Intact Rock Strength ................................................................................................... 16 
6.1.2  Discontinuity Frequency ............................................................................................. 17 
6.1.3  Discontinuity Shear Strength ...................................................................................... 19 
6.1.4  Discontinuity Orientation ............................................................................................. 19 
6.2  Rock Mass Classification ............................................................................................. 20 
6.3  Geotechnical Domains ................................................................................................. 23 
6.3.1  Hornfels Domain ......................................................................................................... 23 
6.3.2  Intrusives Domain ....................................................................................................... 23 
6.4  Rock Mass Shear Strength .......................................................................................... 26 
6.5  Groundwater ................................................................................................................ 29 
6.6  Design Sectors ............................................................................................................. 30 
7  Interramp/Overall Slope Stability Modeling ......................................................... 35 
7.1  Model Methodology ...................................................................................................... 35 
7.2  Results of Interramp/Overall Stability Analysis ............................................................. 37 
8  Bench Design ......................................................................................................... 40 
8.1  Description of Models Used ......................................................................................... 40 
8.2  Methodology ................................................................................................................. 41 
8.2.1  Likelihood of Occurrence ............................................................................................ 41 
8.2.2  Likelihood of Exceeding Shear Resistance ................................................................ 44 
8.2.3  Likelihood of Kinematic Admissibility .......................................................................... 44 
MEL/lb 1CA020 004_Kitsault_FS_Geotechnical_Evaluation_FINAL.doc, Nov. 15, 10, 5:25 PM November 2010
SRK Consulting
Feasibility Geotechnical Pit Slope Evaluation, Kitsault Project Page ii

8.3  Results ......................................................................................................................... 47 
9  Pit Slope Design Recommendations .................................................................... 48 
10 Assessment of Future Geotechnical Work .......................................................... 50 
11 References ............................................................................................................. 51 

MEL/lb 1CA020 004_Kitsault_FS_Geotechnical_Evaluation_FINAL.doc, Nov. 15, 10, 5:25 PM November 2010
SRK Consulting
Feasibility Geotechnical Pit Slope Evaluation, Kitsault Project Page iii

List of Tables
Table 1: Drillholes Oriented and Logged for Geotechnical Data .................................................. 7 
Table 2: Summary of Discontinuity Orientation ............................................................................ 8 
Table 3: Uniaxial Compressive Strength Testing ....................................................................... 12 
Table 4: Triaxial Compressive Strength Testing ........................................................................ 13 
Table 5: Summary of Residual Shear Strengths ........................................................................ 15 
Table 6: Direct Tensile Strength Testing .................................................................................... 15 
Table 7: Discontinuity Sets Delineated for Analysis ................................................................... 20 
Table 8: In-situ Rock Mass Rating (IRMR) Distributions ............................................................ 21 
Table 9: Secondary Hoek-Brown Parameters Stochastic Input ................................................. 26 
Table 10: Results of Overall Slope Stability Modeling ............................................................... 38 
Table 11: Summary of Potential Failure Forming Sets .............................................................. 42 
Table 12: Summary of Discontinuity Set Spacings .................................................................... 44 
Table 13: Composited Results of Backbreak Analysis .............................................................. 47 
Table 14: Summary of Pit Slope Design Recommendations and Expectations ........................ 48 

List of Figures
Figure 1: Site Location Map .......................................................................................................... 2 
Figure 2: Location of Geotechnical Drillholes ............................................................................. 10 
Figure 3: Point Load Index – UCS Correlation Factor ................................................................ 17 
Figure 4: Rock Mass Parameters ............................................................................................... 18 
Figure 5: Distribution of Friction Angles (Zero Cohesion) ........................................................... 19 
Figure 6: Discontinuity Pole Plots ............................................................................................... 22 
Figure 7: Drillhole RQD Cross-Sections ..................................................................................... 24 
Figure 8: Geologic Model and Geotechnical Cross Sections ...................................................... 25 
Figure 9: Rock Mass Shear Strength: Hornfels ......................................................................... 27 
Figure 10: Rock Mass Shear Strength: Intrusives ..................................................................... 28 
Figure 11: Summary of vibrating wire piezometer data from K09-07 (El=595.71) ...................... 31 
Figure 12: Summary of vibrating wire piezometer data from K09-12 (El=548.49) ...................... 31 
Figure 13: Groundwater Pressures Measured in K09-07 ........................................................... 32 
Figure 14: Groundwater Pressures Measured in K09-12 ........................................................... 33 
Figure 15: Pit Slope Design Sectors ........................................................................................... 34 
Figure 16: Explanation of Pit Slope Terminology ........................................................................ 36 
Figure 17: Preliminary Interramp Slope Design Curves: Hornfels .............................................. 39 
Figure 18: Discontinuity Contour Plot for Backbreak Analysis .................................................... 43 
Figure 19: Explanation of Backbreak Terminology ..................................................................... 46 
Figure 20: Maximum Interramp Slope Angle Recommendations ............................................... 49 

List of Appendices
Appendix A: Geotechnical Core Logs 
Appendix B: Laboratory Testing 
Uniaxial Compressive Strength Testing 
Triaxial Compressive Strength Testing 
Direct Shear Testing 
Brazilian Disk Tension Testing 
Appendix C: Slope Stability Modeling 
MEL/lb 1CA020 004_Kitsault_FS_Geotechnical_Evaluation_FINAL.doc, Nov. 15, 10, 5:25 PM November 2010
SRK Consulting
Feasibility Geotechnical Pit Slope Evaluation, Kitsault Project Page iv

Limit Equilibrium Modeling 
Finite Element Modeling 

MEL/lb 1CA020 004_Kitsault_FS_Geotechnical_Evaluation_FINAL.doc, Nov. 15, 10, 5:25 PM November 2010
SRK Consulting
Feasibility Geotechnical Pit Slope Evaluation, Kitsault Project Page 1

1 Introduction and Background
SRK Consulting (US), Inc. (SRK) was requested by Avanti Mining Inc. (Avanti) to carry out a
feasibility level geotechnical evaluation for the Kitsault Project Open Pit in the British Columbia,
Canada (Figure 1).
This report presents a complete description of the methods used to collect pertinent information,
the information so gathered, the analytical tools employed to produce assessments of the
anticipated response of the geologic environments to the development of the open pit and the
recommendations based upon those assessments. The feasibility study (AMEC, 2010) ultimate pit
and current geologic solids provided by Avanti were used as the basis for the evaluation.
MEL/lb 1CA020 004_Kitsault_FS_Geotechnical_Evaluation_FINAL.doc, Nov. 15, 10, 5:25 PM November 2010