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• Complete additional rock stability evaluations in the South Quarry western <br /> face/southwestern corner and eastern face below El. 7,000 and above El. 6,500 to <br /> determine if all or portions of these areas can be safely re-mined to steeper slopes. <br /> • Complete additional geotechnical studies in the South Quarry northwestern face to <br /> support and inform benching configurations for future mining activities. <br /> • Complete additional geotechnical studies in the South Quarry below El. 6,500 to <br /> evaluate geotechnical stability in saturated conditions, as anticipated in Phase IV. <br /> The results of this geotechnical analysis will be included in the future Permit Amendment <br /> required to initiate Phase IV mining operations. <br /> Reclamation: As stated above, geotechnical evaluations will be conducted in areas of observed <br /> slope failures or instabilities before reclamation begins in those areas. Exhibit E — Reclamation <br /> Plan has been updated to include recommendations from Appendix 1. Specifically, in South and <br /> West Quarry benches above El. 7,000 where topsoil backfilling and revegetation is permit- <br /> required, several rockfall benches will be left open for rockfill catchment consisting of a 5- to 10- <br /> foot zone free of fill material every three to four benches. This material-free zone would reduce <br /> the potential for isolated rockfall from traveling down slope and propagating down to the active <br /> mine areas, reducing the risk to mine personnel and infrastructure. These rockfall berms would <br /> remain in place following reclamation for the protection of wildlife and maintenance personnel <br /> accessing the former highwall areas. <br /> Aggregate Industries and HDR appreciate the thorough review of AM07 and your willingness to <br /> provide our team adequate time to reassess our mining approach. If you have any questions <br /> regarding this Adequacy Review response or the contents of the revised AM07 Permit <br /> Amendment document, or if you need any additional information, please contact either Chance <br /> Allen (chance.allen(a-)-lafargeholcim.com, 303.648.1175) or myself <br /> (katherine.garufi(a�hdrinc.com, 720.877.7546). <br /> Sincerely, <br /> HDR Engineering, Inc. <br /> Digitally signed by <br /> Garufi,Katherine Garufi,Katherine Allison <br /> Allison Date:2021.09.03 <br /> 17:33:39-06'00' <br /> Kate Garufi <br /> Senior Project Manager <br /> cc: Chance Allen, Kimberly Dennis, Jeremy Pritchett, Michelle Berger <br /> Attachments: <br /> • Table 1: DRMS Adequacy Review Response —Application Form, Exhibit A - Exhibit S <br /> • Table 2: DRMS Adequacy Review Response —Appendix A—Geotechnical Stability Exhibit <br /> • Construction Material Regular (112) Operation Reclamation Permit Amendment Application: <br /> Seventh Amendment (AM07) to Permit M-1973-021, Aggregate Industries Morrison Quarry, <br /> September 3, 2021 <br />