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December 27, 2023 Page 5-1 <br />Agapito Associates, Inc. <br />5 PROPOSED PILLAR EXTRACTION PLANS <br />Based on the design standards stipulated in Section 4.1, the proposed pillar extraction plans are <br />shown in Figures 5-1 to 5-4. For the purpose of assessing pillar stability during pillar extraction, <br />the panel has been divided into seven separate zones. The zones were chosen to effectively assess <br />the stability of the mains pillars when subjected to the retreating abutment load. The empirical <br />assessment indicates that in all zones, the last line of pillars ahead of the retreating gob attain a SF <br />of >1.4 under front abutment loading. These SFs are considered acceptable for the purpose of pillar <br />extraction retreat. The results of the assessment are summarized in Table 5-1. <br />Table 5-1. Summary of the Stability for the Pillars in Sunset Mains South During Retreat <br />Pillar Line Proportion of Abutment <br />Load (R) <br />Pillar Strength <br />(psi) <br />Abutment Load <br />(psi) <br />Safety Factor <br />(SF) <br />Zone 1 96% 3,407 1,422 2.4 <br />Zone 2 93% 3,407 1,980 1.7 <br />Zone 3 96% 3,559 2,282 1.6 <br />Zone 4 99% 3,720 2,542 1.5 <br />Zone 5 81% 3,116 2,231 1.4 <br />Zone 6 90% 3,369 2,162 1.6 <br />Zone 7 100% 3,659 1,765 2.1 <br /> <br /> <br /> <br /> <br />