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2019 Plan of Operations Modification American Gypsum Company, LLC <br /> in a manner appropriate to water conditions encountered during drilling as described <br /> in Section 7.1. Potential drilling areas are identified on Drawing 06; and <br /> ❑ Develop the new East Pit, including removing an average overburden depth of 20 feet. <br /> The East Pit would be excavated to an anticipated pit floor elevation of 6900 feet amsl <br /> as shown on Drawings 08 and 09.Additional drilling may be required to further explore <br /> the gypsum depth (potential drilling areas shown on Drawing 08). Drilling permits <br /> (including drill hole plugging and reclamation) would be obtained prior to drilling and <br /> drill holes would be plugged in a manner appropriate to water conditions encountered <br /> during drilling as described in Section 7.1. <br /> ➢ Material hauling: <br /> ❑ Haul gypsum to American Gypsum's wallboard plant or existing on-site stockpiles; <br /> ❑ Haul overburden and intraburden to new road construction areas, on-site storage, or <br /> to inactive pit areas for progressive reclamation; and <br /> ❑ Haul intraburden to in-pit storage areas (inactive areas of the pits) and maintaining <br /> stockpiles. <br /> ➢ Progressive (or concurrent) reclamation (Drawings 06 and 08): <br /> ❑ Backfill inactive pit areas with overburden and intraburden to 2.5H:1V overall slopes <br /> where possible. <br /> ➢ Final reclamation (Drawings 11 through 13): <br /> ❑ Regrade any areas within the Upper Pit, East Pit, or access roads associated with the <br /> proposed disturbance area (listed above)to 2.5H:1 V slopes or flatter, achieving 3H:1 V <br /> where possible; <br /> ❑ Remove culverts and associated riprap collars/aprons through road crossings, <br /> including excavating road fill to pre-construction topography to expose culverts, re- <br /> establishing natural drainages at pre-construction grades, and regrading remaining <br /> road fill to 2.5H:1 V or shallower; <br /> ❑ Install riprap or other erosion protection measures where necessary (such as re- <br /> established native drainage channels); and <br /> ❑ Revegetate disturbed areas. <br /> Drawing 04 shows types and locations of disturbance associated with the proposed Modification. <br /> 6.3 Period of Operation <br /> Mining in the Upper Pit is ongoing; based on current mining rates (approximately 500,000 tpy), <br /> mining in the Upper Pit can continue to support American Gypsum's wallboard plant needs for an <br /> additional 15 to 25 years (depending on the quality of gypsum encountered). For the East Pit, <br /> clearing and grubbing/overburden removal is anticipated to begin in 2021. The East Pit is <br /> expected to support mining activities for an additional 26 years (duration may vary depending on <br /> the quality of gypsum encountered). <br /> Am Gypsum Poo Mod ISSD 20190909 September 2019 [22] <br />