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at one stage, the next stage of the operation is designed and implemented. The steps used in the • eviously for to the South Quarry in Amendment No. 3 aze illustrated in Figure D-1, "Observational Method" Decision Tree. /Using this method, stage one of the excavation process will consist of slopes inclined at 1H:1V, or less, p3 ? generally consisting of 80 ft highwalls and 80 ft benches. Observations will consist of mapping rock mass features, testing intact specimens and reviewing stability analyses in light of updated information. ` / `~ Stage two will consist of steepening the slopes to a maximum of IH:2V, consisting of 80 ft highwalls and / `~ k 40 ft benches if rock mass conditions are found to be adequate to safely support this slope angle, The g' general approach to these evaluations is to: 1) establish a baseline of rock mass characteristics and .t ~ perform stability analyses of proposed slopes based on those rock mass chazacteristics; and 2) after the 'Qf rock mass has been exposed and evaluated, compaze the actual conditions with the baseline conditions ~~ • ~ •r to determine whether changes in proposed slope configurations aze appropriate. 4-03. QUARRY DEVELOPMENT NARRATIVE The maximum final buildout configuration for the Quarry is presented in plan view in Figure D-8, Exhibit D -Phase lIIC (Final) Mining Plan. Intermediate phases have been included in the proposed mine development to address reclamation of the mine, handling of surface water, and other operations considerations. Typical highwall and bench configurations are presented in Figure D-9, Typical Highwall and Bench Cross-Section. The standard design configuration is 80 ft highwalls and 40 ft benches. Several exceptions to the standard are noted including: 1) the slope failure study and remediation azea at the east wall of the Central Quarry, 2) flatter configurations along upper portions of western exposures to reduce • visual impacts, and 3) other areas as necessary to address slope stability concerns in azeas of lower quality rock, unusually high rock slopes, and key design azeas near the proposed reservoir sites. Highwalls will generally be developed in two 40 ft high levels which correspond to the typical drill length for shot holes. Benches are designed to be either 40 ft or 80 ft wide depending on requirements for reclamation and stability. The upper benches on western quarry walls, which may be highly visible to viewers outside the quarry from the east and southeast, aze designed to be either 40 ft x 60 ft (highwall ~ x bench) or 80 ft x 80 ft to accommodate a higher wedge of soil for reclamation, revegetation, and reduced visual impact. This wnfiguration will result in a relatively small visual impact upon completion Q` y` of the reclamation process. Below these upper three benches, the maximum development plan is for 80 ft highwalls and 40 ft benches. Shallower slope angles may be required based on future geotechnical ~~ ~ evaluations. CJ/;'~~~ Rock will be removed by conventional blasting, loading with an excavator and/or a loader, and I~~J1 _ transportation with 50 or 85 ton trucks for the majority of the quarry. For deep portions of the quazry, it is likely that truck haulage will not be praaical due to the potentially steep and/or long grades for haul roads. Given these conditions, lower quarry development may utilize in-pit crushers and/or conveyors to transport crushed product to the existing process azea between the North and Central Quazries. In-pit mobile crushing with associated field conveyors will be used as needed to convey primazy material (probably all 6-in. minus) to the existing plant. Phase 1 (complete mining in the Central Quarry and initial mining in the North Quarry) is estimated to contain approximately 11.5 million tons of material and it is anticipated that it will be completely . •~•e.a>o IV-3 ~~~