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Mr. Forrest Luke <br /> Page 5 of 7 <br /> July 2020 <br /> the A-pit and include it in the stability analysis performed by AAI. <br /> On 16 July DRMS received TMI's response to the above question and is reviewing the information <br /> submitted. <br /> 4.14.2 General Grading Requirements <br /> DRMS June 2020 <br /> DRMS notes that Trapper committed to a minimum safety factor of 1.5 to ensure long term <br /> global stability in both the L and Ash Pits, exceeding the minimum requirements (1.3), of both <br /> rules 4.12.2(1)(b) and 4.27.3(3). <br /> DRMS notes that backfilling and grading in the Ash Pit adequately minimizes erosion and <br /> slippage,providing a surface for topsoil replacement and adequate methods of seedbed <br /> preparation. As per Rule 4.14.2 (5). <br /> The above mentioned rule is adequately met. <br /> 4.23.2 Auger Mining <br /> DRMS notes that Trapper provided information applicable to the above mentioned rule. Trapper <br /> committed to optimizing coal recovery based on the proposed highwall mining plan, ensuring the <br /> minimum static safety factor ensuring long term global stability. <br /> The above mentioned rule is adequately met. <br /> 4.27.2(3) Operations on Steep Slopes <br /> DRMS July 2020 <br /> As per the Agapito Associates Inc Geotechnical Evaluation and Trapper's Appendix B (Steep <br /> Slope Mining Variance from Approximate Original Contour), a depth based approach for spoil <br /> backfill was employed in the analysis. <br /> Based on the "depth-based" approach, spoil of coarser/heavier particles are deposited at <br /> the bottom with finer/lighter particles are deposited at the top. It is unsure to the Division <br /> how Trapper plans to implement this during backfilling and grading of the L- and A-pits. <br /> Based on the depth based approach, spoil of coarser/heavier particles are deposited at the <br /> bottom with finer/lighter particles deposited at the top. The Division is unsure how TMI <br /> plans to implement this scenario during backfilling and grading of the L and A pits. For <br /> additional information on DRMS's analysis please see the adequacy memo dated <br />