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r <br /> transferred to transport vehicles and placed in the designated areas within the East cell, north of Highway 7 <br /> to await transfer via conveyor or truck to the off-site processing area. <br /> • The slurry wall liner for the West and East cells will be installed concurrent with mining in the South cell. <br /> Once the slurry wall is installed the West and East cells will be dewatered. The deposit will be dry mined <br /> using dewatering trenches and pumps within the slurry lined area. Prior to excavation of each mining <br /> phase,trenches will be cut along the perimeter of the cell area to begin dewatering the sand and gravel <br /> material. The trenches will extend through the overburden and alluvium to bedrock. Pumps will be used to <br /> remove the groundwater that drains from the deposit within the lined cell. If necessary,water from the <br /> trenches will be circulated through a settling pond prior to being discharged to adjacent drainage ditches <br /> and/or the South Platte River(see Exhibit C Mining Maps). As excavation begins,the mining cell and <br /> dewatering trenches on the cell floor will continue to collect any water entering the lined cell, keeping the <br /> deposit material relatively dry. The collected water will be directed to settling ponds within the cells or near <br /> the final discharge point to South Platte River. It is anticipated that dewatering will be completed within the <br /> slurry wall lined mining area within 12 months and dewatering throughout the life of the mine will be limited <br /> to precipitation,stormwater runoff that drains into the mining cells, and minor amounts of groundwater. <br /> Earth Movinq <br /> Setbacks from the top of slope of each mining cell to the proposed permit boundary or man-made structures not <br /> owned by the applicant will generally be 30 feet or greater. Specific setbacks from Highway 7 and Tucson Street <br /> also account for future expansion of the roadways. The perimeter setbacks from the permit boundary are shown on <br /> Exhibit C-Mining Maps <br /> These setbacks were determined in combination with Adams County regulations and the Slope Stability Analysis <br /> prepared by Tetra Tech provided herein in the Geotechnical Stability Exhibit. The setbacks reflect the Factors of <br /> Safety in the Proposed Slope Stability/Geotechnical Analysis Policy in the DRMS memorandum dated May 16, 2018. <br /> Areas to be mined will be prepared by removal of topsoil and overburden. Each preparation area may be as much as <br /> 100 feet wide along the anticipated mining face. Usually,only enough area is stripped and prepared to provide the <br /> estimated needs for the next 10 to 14 months of mining. Surface topsoil material will be stripped separate from the <br /> underlying,deeper subsoil or overburden material. This topsoil layer contains most of the soils organic matter and <br /> will be stockpiled separately for use in reclamation. Once the topsoil has been removed,the rest of the overburden <br /> will be stripped and stockpiled separate from the topsoil. <br /> When the alluvial material is exposed and sufficiently dewatered,the aggregate material will be recovered using <br /> equipment typical for sand and gravel mining operations. Aggregates in the South cell will be wet mined using <br /> excavators and/or draglines. In the West and East cells,the aggregates will be mined using conventional dry mining <br /> methods. Earth moving equipment may include, but is not limited to,dozers, loaders, scrapers, and excavators as <br /> mining progresses to a depth of 20 to 40 feet below the surface. The alluvial material is an unconsolidated deposit <br /> and,therefore, no blasting is required. The aggregate material from the cell will be temporarily stockpiled within the <br /> cell,conveyed to the staging area, or immediately transported off-site for processing. During mining and reclamation <br /> activities,watering trucks for dust control will be used as needed. <br /> The active mining face will extend no more than 4,000 feet in length. During mining in the South cell,the mine walls <br /> will beat or near the angle of repose, approximately 2H:1V. During mining and prior to reclamation in the West and <br /> East cells,the mine walls will be a nearly vertical to%H:1V slope(see Exhibit C, Mining Maps). Mining will progress <br /> down to the depth of quality aggregate material. Backfilling and/or grading of side slopes may follow behind the <br /> mining activities before mining in the cell is complete. <br /> Aggregate Industries Tucson South Resource <br /> Permit#M-2004-044112 Permit Amendment <br /> Page D-4 <br />