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H S ,utt _. >;r„ . I-,.-V,:, �'.r # 1\J1a'y .202 <br /> initiated during Phase 1, if necessary. Primary activities in this phase include the mobilization <br /> and placement of the heavy equipment, a temporary work trailer, screening and wash <br /> equipment, temporary vault-and-haul septic trailer, and potable water. This phase will also <br /> include the installation of the secondary containment structures associated with the Spill <br /> Prevention, Control, and Countermeasure (SPCC) requirements for fueling activities <br /> (Appendix F). Equipment for this phase will include, but not be limited to, a bulldozer, track- <br /> hoe, and a 35-ton haul truck. <br /> 1.1.8.2.1 Water Handling <br /> Phase 1 water management activities will continue throughout this phase. No additional water <br /> diversions nor impoundments will be required during this phase. Irrigation return flows will be <br /> conveyed across the property without change. <br /> 1.1.8.3 Mining Extraction (Phase 3) <br /> Phase 3 includes excavating and processing operations for the 12.39 acres of mining area <br /> within the 19.00 acres of disturbance. The mine will use conventional mining equipment for <br /> this phase, including but not limited to a long-reach excavator, a bulldozer, track-hoe, <br /> screening plant, wash plant, crusher, and a 35-ton haul truck. This section describes the <br /> mining methods, earthmoving, and size of the areas anticipated to be mined at the 30%, 60%, <br /> and 100% mining development of the 12.39 acres over three to five years. <br /> Size of Area Worked at 30% <br /> The estimated area to be mined at 30% is approximately 3.72 acres (depicted in Figure 2) <br /> and amounts to approximately 87,843 CY of mined material. <br /> Size of Area Worked at 60% <br /> The estimated area to be mined at 60% is approximately 7.43 acres (depicted in Figure 3) <br /> and amounts to approximately 175,686 cumulative CY of mined material. <br /> Size of Area Worked at 100% <br /> The estimated area to be mined at 100% is approximately 12.39 acres (depicted in Figure 4) <br /> and amounts to approximately 292,810 cumulative CY of mined material. <br /> 1.1.8.3.1 Mining Methods and Earthmoving <br /> This phase of the project will include mining, stockpiling of material for screening, washing <br /> and crushing processes. <br /> The working surface of the mine will consist of the alluvial gravel surface that is exposed after <br /> removal of the overburden. A long-reach excavator stationed on the edge of the pit will <br /> excavate material to a depth of approximately 20 feet. The pit will fill with water as excavation <br /> proceeds, forming a pond that expands as the excavator continues to remove material. The <br /> pond water will be in direct contact with the water table of the Colorado River via lateral <br /> migration through the underlying permeable gravels. Excavated material will be piled on the <br /> edge of the pond for approximately 24 hours, to allow drainage of free water from the material <br /> back into the pond. This will occur through a combination of surface runoff into the pond and <br /> infiltration of the free water through the underlying gravels into the pond. <br /> Sideload dump trucks will travel to the pond edge and will be loaded with the dried material <br /> daily. The dump trucks will transport the dried material from the active excavation area to the <br /> 1-13 <br />