2021-12-29_PERMIT FILE - M2021009 (9)

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30. Please describe how the two waste rock landforms (including the toes) will be accessed after mine phase 1, when these two features merge. Will roads be constructed along the side(s) of the waste rock landforms? Even after each lift is reclaimed, the waste rock landform will require continued access for maintenance and reclamation. Please ensure all proposed roads are shown on the applicable mine phase maps in Exhibit C. The 2.2H:1.OV slopes of the WRLs will be created and reclaimed as mild enough slopes for tracked mobile equipment to access the base of either WRL. Any as needed slope maintenance will be completed by small tracked equipment. Therefore, no formal road will exist to the toe of either WRL following reclamation of lower lifts. In the event that tracked equipment must cross a reclaimed area, directly after crossing and/or as seasonal appropriate, seed and/or tree plantings will be undertaken to reclaim any impacted area. 31. Figure 4 is a schematic typical cross section of the proposed quarry highwalls, showing the top gravel layer to be mined at the same near vertical slope gradient and backfilled at the same 2H:1 V slope gradient as bedrock highwalls. Please describe the approximate portion of highwalls proposed for mine phase 3 which are expected to consist of gravel benches. Will only the southern highwall of the phase 3 quarry have gravel benches?Are the proposed gravel benches expected to have the same competency at the proposed mining configuration? Lastly, does the geotechnical stability analysis provided in this application factor in the portion of highwalls to be composed of gravel rather than bedrock? The previous submittal included gravel mining during phase 3; however, gravel mining will now occur during phases 2 and 3. The approximate portion of phase 2 proposed backfilled mine slopes that will consist of gravel mining is —300 feet and —900 feet during phase 3 mining. However, the maximum exposed mining highwall (prior to backfilling) at any given time will be 500 feet long. Yes, the southern highwall of phases 2 will have gravel benches while the southern highwall and west facing highwall of phase 3 will feature gravel benches. Please refer to the Geotechnical Stability exhibit which discusses gravel mining highwalls for additional information on gravel competency. 32. On page D-14, the application states a stormwater/safety berm will be constructed along the upper crest of each 50 foot tall highwall bench to divert stormwater and to catch any rock falls. Please describe how these berms will be constructed. Additionally, please describe how these berms will be designed to minimize rockfall hazard, particularly where highwalls will rise above the realigned Central City Parkway in the southern access corridor(to be created during mine phase 2). According to Figures C-4 and C-5, these highwalls will rise approximately 300 feet above the road on its western side and 650 feet on its eastern side during mine phase 2, then 300 feet on its western side and 330 feet on its eastern side during mine phase 3 (and for final reclamation). "Highwall" as detailed in the Division's Preliminary Adequacy Review are referring to reclaimed slopes of 2.OH:1.OV which are not highwalls but are instead final mined and reclaimed slopes with no potential for rockfall hazard. The page D-14 (previous submittal page) reference to 50-foot referred to the catch bench crest- to-crest width of each bench, not the height which will be no higher than 25-feet. Safety and stormwater berms will be constructed from coarse blasted material resulting from the most recent and appropriate blast relative to the current active mining area. Berms will be graded and December 2021 10 M Lewicki 81 Associates