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NEWMONT NeAl ,.PtM,,,,,� <br /> Newmont Response: <br /> Settlement of the SGOSA has been addressed in Section 5.2 of the updated design report, which is <br /> provided in Attachment 13. <br /> DRMS Comment(italics): <br /> 81. Section 5.2, Schist Island Backlill Settlement. The Division is concerned about the potential <br /> differential settlement across the abrupt transitions cat bench crests in the backfilled Schist Island <br /> pit, especially inhere shallow (less than 25 lb or no fill transitions to fill depths 40 to 80 feet deeper <br /> .fall across the underlying bench crest (e.g., stations 3+50, 8+50 and 8+90on Drawing.419 and <br /> horizontal positions 2240, 2350, 3 230 and 3 2-0 in Appendix G). Site experience with the similarh• <br /> constructed mill platform .suggests settlement on the order of'a.foot can be expected when loaded <br /> with 100 to 150 feet of ore on areas that have 20 to 50 feet ofcompac•ted engineered fill over fairly <br /> uniform base(i.e., no abrupt transitions across a bench). It is not clear front the discussion in this <br /> section whether this potential for significant differential.settlement was adequately addressed The <br /> narrative states a finite element analysis was used but there is no discussion on or rationale for the <br /> selection of•the horizontal and vertical grid spacing used in the analysis. One would expect if the <br /> grid .spacing was too large, the abrupt transitions here mat• not be adequately evaluated This <br /> .section has not provided anv interpretation of the figure shown in Appendix G. .-lre the settlement <br /> numbers regional or mccrimums over short distances".4 displacement grid(similar in concept to a <br /> flow net) might provide a useful assessment and a helpful interpretation. Furthermore, given the <br /> selection of'Poisson:s Ratio and Young's_11odulus from published values (as opposed to testing site <br /> materials) one would expect.some model calibrations might be in order, perhaps using settlement <br /> data available for the area involved in the 2018 V'LF2 liner failure. The Division requires additional <br /> discussion and background on the settlement model to provide assurance that the potential <br /> differential settlement across abrupt transitions in fill depth have been adequately considered. <br /> Newmont Response: <br /> Differential settlement across the abrupt transitions at bench crest in the backfilled Schist Island <br /> Pit has been evaluated and is presented in Section 5.2 of the updated design report. <br /> Grid spacing is addressed in section 5.2.3 of the updated design report. <br /> A back analysis of the data available from the area involved in the 2018 VLF 2 liner failure has <br /> been used to determine the elastic modulus of on-site till materials and is discussed in Section <br /> 5?2 of the updated design report which is provided in Attachment 13. <br /> DRMS Comment(italics): <br /> 82. Section 5.2.3 Results& Section 5?.4 Conclusion. The last statement on p. I- "assuming the strains <br /> are distributed along equally from the edge gf*the bac•kfill to the location of mayintum.settlement <br />