WKP PFS – Geotechnical Section Approved by: Approval Date: TBA OceanaGold PEX-000-PLN-046-A Page 21 of 22 Figure 19: Stability of waste pass & ore pass system In the southern section of the mine, the waste pass and ore pass system are located between two ore bodies. Figure 19 shows that extreme stress damage is likely to occur in the waste pass and ore pass system if the mining sequence is not carefully managed. Figure 20 shows the improvement to the rock mass stability if central pillars are used at each stope access intersection. In the model, a 30m long pillar (two stopes) were left on the south side of the access, and a 15m long pillar (one stope) was left to the north of the access. These pillars would be recovered in a bottom-up sequence near the end of the life-of-mine. Figure 20: Stability of waste pass and ore pass system with central pillars
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