REVISIONS. App Sud. App PC. App Thom AA 2014/10/28 AA 2014/11/24 AA 2015/06/24

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1 1/5 REVISIONS Rev Description Rev n by Sud PC Thom VB LH Clyd Act Issue Date YYYY/MM/DD 1 New Specification 2014/10/ /10/28 N/A N/A N/A N/A N/A N/A 2014/11/12 2 Drawing Revised See endix A 2014/11/ /11/24 N/A N/A N/A N/A N/A N/A 2014/11/24 Drawing Revised See endix A 2015/06/ /06/24 N/A N/A N/A N/A N/A N/A 2015/06/24 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 licable

2 2/5 1.0 PURPOSE This specification describes the minimum requirements for the design and construction of the shotcrete dump walls used in mining stope. In Vertical Retreat Mining (VRM), after a stope is mined it is backfilled for most part with rock. The rock fill is normally dumped into the stope by Load Hauling Dump (LHD) from above. The purpose of the dump wall is to prevent the LHD from falling into the open stope while dumping. Therefore the dump wall should be rigid enough to resist impact from the LHD. 2.0 APPLICATION This specification is applicable to shotcrete barricade at mines in the Sudbury Region as follows: Type lication Description Mine licable 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. The remote stand shall be fabricated and erected in accordance with Vale standards. 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-0048 Dump wall - In Rock Sidewalls. Dump wall - In Sandfill Sidewalls.

3 /5 4.0 TYPES OF BARRICADES Two different designs of dump walls are included in this specification. Dump wall installed against rock sidewall and dump wall installed against sandfill wall. Dump walls installed against rock side walls. This type requires the side walls to be solid rock or shotcrete on solid rock. The floor (base of rails) where the dump wall is resting shall also consist of solid rock. This type does not apply to fractured weak rock or sandfill walls. This dump wall consists of shotcrete block reinforced with four steel cables or steel chains and each cable or chain is anchored into rock using Williams or Dwyidag rock anchor systems. No other rock anchoring systems should be used without the approval of the Engineer in writing. Refer to design drawings for the complete construction details. This type of dump wall is shown and detailed on the following drawings: D-0047 Dump Wall- In Rock Side Walls. Dump walls installed against Sandfill side walls. This type requires the side walls to be sandfill with shotcrete face. This wall cannot be installed to exposed faces of sandfill without shotcrete. The floor (base of rail) where the wall is resting shall consist of solid rock with roughened surface to generate friction between the rock and the shotcrete. This wall consists of arched shotcrete block where most of the strength is from the compressive arching effect and the friction between shotcrete and rock. The design was load tested using full scale model and loading. Refer to design drawings for the complete construction details. This type of dump wall is shown and detailed on the following drawings: D-0048 Dump wall- In Sandfill Side Walls. 5.0 GENERAL The dump wall must be inspected and constructed in accordance with the design drawings. No deviations are permitted without the prior approval of the Engineer. All dump walls shall be used, inspected and maintained in accordance with the design drawings, all mines standards and this standard. The dump wall safety checks listed on the design drawing shall be monitored and verified on regular basis. The following items are very critical for the installation and safe use of the dumpwall:

4 4/5 Dump walls must be built within the permissible dimensions shown on the design drawings. Do not exceed the width/span shown on the design drawing. Do not exceed the design loads and the LHD travelling speed specified on the drawings. Ensure that the shotcrete is placed and compacted properly to ensure no air voids within the wall thickness. It is recommended to pour shotcrete dumpwall without any cold or construction joints. If a construction joint is a must, make the joint horizontal and at mid height of the wall. Dump walls are designed based on best engineering judgment, LHD sizes and weight, and LHD speed. Any modification to the dump wall design may require additional testing. 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. 6.0 APPENDICES endix A: Revision and Transition Notes

5 5/5 endix 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 No D-0047 Added optional embedded 4 PVC pipes for blasting purposes. Revision 2 Drawing No D Dump block plan dimensions and Table 1 added, as requested by mine. Revision 1 New Specification Drawing No D-0047 was formerly Drawing No D-05626, and is now part of this specification.