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4.Environmental Analysis _ slopes exposed during active mining would reach an inclination of 3/4:1 (H:V) or equivalently, a gradient of 53 degrees. These temporary slopes would be unsupported, non-engineered,or otherwise unfinished and could be susceptible to failure and raveling(localized collapse of unconsolidated material at edge of slope)during mining operations or during a major earthquake — event. If these slopes become saturated during the rainy season, slope conditions could worsen and the potential for slope failure could increase. Permanent slopes under the reclamation plan are proposed at inclination of 2:1 (H:V) without intermediate benches. Slopes at 2:1 (H:V)are — typically more stable than steeper slopes but can be subject to failure under earthquake ground motion and localized surface failures from erosion or saturation if not adequately engineered and constructed with slope protection measures. Failure of completed 2:1 (H:V) slopes could — adversely affect efforts to reclaim the quarry by initiating future slope failure,causing excessive erosion, and limiting reuse of the reclaimed area for agricultural purposes. _ Landslides and shallow slope failures in non-engineered temporary slopes would be restricted to localized areas. If slope failure occurred in active mining areas,the down slope displacement of _ soil and rock could cause injury to workers in the immediate vicinity or could cover or compromise the stability of equipment working at the base of the failed slope. Given that mining operations involve select pieces of heavy excavation and earthmoving equipment with a limited _ number of operators, there would be a limited number of people exposed to slope failure hazards. In non-active mining areas with steep slopes, slope instability and failure would,in most cases, not result in injury or damage because workers or equipment would not typically occupy these areas. In some areas,failure of steep temporary slopes could cause failure above the slope in unmined phases. For example, slope failure could adversely affect areas adjacent to Phase H and IV-A where steep 3/4:1 (H:V)temporary slopes border the proposed plant site. However, surface — failure would likely affect only the upper edge of the slope and would not extend outside the setback at the edge of slope. Significance Criteria CEQA defines a significant effect on the environment as a substantial, or potentially substantial, — adverse change in the physical conditions within the area affected by the project. A geologic, soils-related,or seismic hazard impact would be considered significant if it would result in any of the following, which are adapted from CEQA Guidelines: • Expose people or structures to potential substantial adverse effects, including the risk of injury, or death, or property loss, or present a long-term potential adverse effect to reclamation efforts after mining is complete: — Rupture of a known earthquake fault8,as delineated in the most recent Alquist-Priolo Earthquake Fault Zoning Map issued by the State Geologist for the area or based on other substantial evidence of a known potentially active fault(Refer to Division of Mines and Geology Special Publication 42.); — Strong seismic ground shaking; 8 Per CEQA Guidelines,a known earthquake fault is one that has been delineated on the most recent Alquist-Priolo Earthquake Fault Zoning Map issued by the State Geologist for the area or based on other substantial evidence of a known fault.Refer to CDMG Special Publication 42. RMC Pack Vemalis Quarry Mining and Reclamation Project 4.7-16 ESA 1203015 Draft Environmental Impact Report May 2006