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JUn MIT 1 .5, 008 <br />PiWe 45 <br />• Global instability was initially triggered by buckling of the floor in G-Dip Pit. Instability <br />would likely have occurred under these conditions, regardless of G-Dip flit floor <br />buckling, when mining reached L-Scam. <br />5.2 UNDF.RSTANDINC m MINE PLAN <br />-5.2.1 Z-Dih Pit Wining Plan <br />The mine plan for first portion ofZ.-Dip Pit is shown in Figure 31. Dip mining is planned <br />to progress eastward along strike. The mine plan for this area was modified after the landslide <br />event to include a barrier pillar between the old G-Test Pit area and the new Z-Dip Pit area. The <br />Z-Dip area hillside has old mining downdip in which mining opens the hillside on two sides. <br />similar to the pre-landslide conditions of the G-Pit area. The barrier pillar provides a 150-fl-wide <br />buttress between the /-Dip cuts and the old G-Test Pit plus an additional buttress is provided by <br />the spoils that have been piled in the old G-Test Pit area. This barrier pillar is considered <br />conservative and takes into account ground disturbance extending uphill from G-West Pit mining. <br />This disturbance is documented as surface cracking (Figure 32). <br />a;, A <br />f , 1? 111(L-^J <br />n, N N ?t4_ N N V <br />, m44 <br />Figure 31. Mine Plan for First Part of Z-Dip Pit <br />The stability of the Z-Dip hillside was analyzed because a minor highwall failure had <br />occurred in G-Test Pit similar to the G-Strike Pit failures. The analysis used the same rock <br />properties and groundwater conditions assumed in the landslide back-analysis study. Analysis <br />Agapito Associates. Inc.