Rev Description Revision by Approved by

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1 1/5 Rev Description Revision by Approved by Issue Date YYYY/MM/DD 1 New Specification 2 See Appendix A Inspection Port requirement changed-see Appendix A 2016/02/ /02/ /02/01 Sud = Sudbury, Ontario, PC = Port Colborne, Thom = Thompson, Manitoba, VB = Voisey s Bay, LH = Long Harbour, Act = Acton, England, Clyd = Clydach, Wales, N/A = Not Applicable

2 2/5 1.0 PURPOSE This specification describes the minimum requirements for the design and construction of shotcrete barricades used for slurry backfill in mining stopes. In Vertical Retreat Mining (VRM), after a stope is mined it is normally backfilled with sandfill or slurry backfill. The shotcrete barricade is located at the base of the stope and designed to retain the fill hydraulic pressure during the backfilling of the mined stope. 2.0 APPLICATION This specification is applicable to shotcrete barricade at mines in the Sudbury Region as follows: Type Application Description Mine Applicable Drawings 1 Installations against Rock walls All D Installations against Sandfill walls All D REFERENCE DOCUMENTATION The following documents were used in the development of this document or have instructions and procedures applicable to it. They shall be used in their most recent revision. SPEC-100 Cast-In-Place Concrete AMS All Mine Standards (Vale Sudbury). The following drawings form part of this standard and shall be used in their most recent revision: D D Shotcrete Barricade for Slurry Backfill - In Rock walls. Shotcrete Barricade for Slurry Backfill - In Sandfill walls. 4.0 TYPES OF BARRICADES Two different designs of barricades are included in this specification: Barricade installed against rock wall Barricade installed against sandfill wall.

3 /5 Barricade Installed Against Rock Wall This type of barricade requires the side walls to be solid rock or shotcrete on solid rock. This type does not apply to fractured weak rock or sandfill walls and is applicable to a maximum drift width of 0 feet. Refer to design drawings for drift width, radius and maximum pressure, as these are specific to each installation. This type of barricade is shown and detailed on the following drawing: D-0077 Shotcrete Barricade for Slurry Backfill - In Rock Walls. Barricade Installed Against Sandfill Wall This type of barricade requires the side walls to be sandfill with shotcrete face. This wall does not apply to exposed faces of sandfill without shotcrete. This type is applicable to a maximum drift width of 20 feet. Refer to design drawings for drift width, radius and maximum pressure, as these are specific to each installation. This type of barricade is shown and detailed on the following drawing: D Shotcrete Barricade for Slurry Backfill - In Sandfill Walls. 5.0 GENERAL The barricade must be inspected and constructed in accordance with the design drawings. No deviations are permitted without the prior approval of the Engineer. All barricades shall be used, inspected and maintained in accordance with the design drawings, all mines standards and this standard. The following items are very critical for the installation and safe use of the barricade: Build the barricades within the permissible dimensions shown on the design drawings. Do not exceed the design pressures shown on the design drawing. Ensure the drains are working properly to make sure the allowable pressure is not exceeded. Pour sandfill in lifts as specified on design drawings. Ensure the shotcrete is placed and compacted properly to ensure no air voids or cold joints within the wall thickness The Shotcrete shall have at least 20 MPa compressive strength prior to use and start of backfilling. The number of days or hours required to obtain this strength depends on the shotcrete mix used by the mine. Each mine shall perform enough tests to determine the number of days or hours required to attain the required concrete strength.

4 4/5 6.0 APPENDICES Appendix A: Revision and Transition Notes

5 5/5 Appendix A: Revision and Transition Notes (Revisions are listed in reverse chronological order with the most recent revision at the top. Revision notes describe: what was changed, why it was changed, and the plan to implement the change, including whether changes are retroactive) Note: The revision notes are a summary of the changes and may not necessarily be a complete list. Revision Drawing D-0077 Note 14 revised Inspection Ports changed from Required to Optional providing that the mine establish other means and methods to indicate the level of sandfill poured. (as requested by Creighton Mine) Revision 2 Drawing D-0077 revised to show 2 optional 4 dia fill pipes, as requested by Creighton mine. Note 19 added and Section A-A revised. Revision 1 New Specification - The drawings that form part of this speciation were existing drawings that have been renumbered to suit the Engineering Standard Drawing Series. The following drawings have been renumbered: Old Number New Number Description D D-0077 Shotcrete Barricade for Slurry Backfill - In Rock Walls D D Shotcrete Barricade for Slurry Backfill - In Sandfill Walls.