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Chavers Mining Resource <br /> DRMS Permit No.M-2015-030 <br /> Amendment No.2(AM-02) <br /> February 2023 <br /> Page 7 <br /> contractors to obtain assurances that backfill materials are free of contaminants and are <br /> native or natural materials. ASCI will exercise every effort to learn as much as <br /> reasonably possible about the backfill materials received at the Site to ensure that those <br /> materials are free of contaminants. All backfill materials will be inspected upon entry to <br /> the Site and while being unloaded using visual and/or olfactory methods to ensure no <br /> potentially contaminated materials are received. If evidence of possible contamination is <br /> observed, loads will be rejected and will not be allowed to be left on-site by the <br /> contractor. No contaminated materials will be accepted or allowed on-site.Any <br /> asphalt or concrete materials received will continue to be diverted to the recycled <br /> aggregate materials operation at the Site. <br /> ■ Backfilling Process: After an area of the property has been mined of sand and gravel, <br /> Backfilling operations will begin once they can be safely conducted. ASCI will conduct <br /> backfill operations concurrent with mining operations whenever possible. ASCI will not <br /> exceed exposed active mining and backfill pit areas of approximately 20 acres at any one- <br /> time. Backfill material will be imported to the Site with articulated dump trucks and/or <br /> highway dump trucks. The material will be placed and spread in one (1) to two (2)-foot <br /> lifts using haul trucks,bulldozers, excavators, and/or loaders. Compaction will take place <br /> during the filling process, as haul trucks and heavy equipment traverse over the fill. <br /> Temporary excavation slopes and temporary stockpiled material slopes may range from <br /> 1:1 to 3:1 depending on soil conditions in the mine. All slopes will be maintained for site <br /> safety and to minimize material erosion. Areas will be backfilled to a rough grade(i.e., <br /> within approximately 2 - 3 feet of final grade). <br /> ■ Gradin and Topsoil: Once the backfill is near rough grade across the Site, the surface <br /> contours of the affected area will be graded to approximately six(6) inches below the <br /> final grade across the Site. After contour grading is complete, a topsoil cover <br /> approximately six(6) inches thick will be placed on top of the backfill to reach <br /> topographic elevations prior to mining(i.e., final grade). The final grade will control <br /> water runoff, erosion, and siltation to protect all areas outside the mine and allow surface <br /> drainage to flow gently as sheet flow to the northeast, consistent with pre-development <br /> drainage. <br /> To ensure grading requirements are met, elevations will be checked periodically by ASCI <br /> during the reclamation process. This will continue until the final grade is achieved with <br /> backfill materials and topsoil cover. A final topography survey will be conducted by <br /> ASCI after topsoil has been placed,but before seeding occurs to ensure that the Site <br /> topography is at pre-mining elevations and sloped for positive drainage. All surveys will <br /> be conducted by aerial drone. The allowable vertical variation will be approximately one <br /> (1) foot given that the final topography will be slightly undulating in areas to mimic the <br /> original landform. Once topography across the Site is within acceptable limits, ASCI will <br />