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4.7 Geology,Soils,and Seismicity quarry embankments will be stable with a factor of safety greater than 1.5. Similarly,the th. proposed 2:1 (H:V) slopes along the west and north sides of the quarry should be stable with a static factor of safety exceeding 1.5. The pseudo-static analysis determined that during earthquake 6. ground shaking, the quarry slopes should remain stable with an earthquake factor of safety of 1.2 or greater. The proposed permanent reclaimed slopes of 2:1 (H:V) should also be stable with a static factor of safety over 1.5 and a pseudo-static factor of safety greater than 1.2. The factors of safety values meet or exceed the criteria industrial standards established by the Army Corps of Engineers,the Federal Emergency Management Agency,Caltrans,California Department of Water Resources, and Division of Safety of Dams(Kleinfelder, 2005). The factor of safety for the ` permanent slope configuration exceeds the minimum factor of safety established by the San Joaquin County Ordinance for Quarry Excavations for near surface and deep-seated failure of slope. Temporary cut slopes must comply with the Cal OSHA Code of Regulations and/or Federal OSHA Code of Regulations as applicable. The proposed permanent configuration of the quarry slopes are 2:1 (H:V)at 100 feet in height without terraces. As discussed above, the slope stability analysis(Kleinfelder,Inc.,2005)determined that these slopes would remain stable under static and pseudo-static conditions. However,this configuration does not comply with Chapter 9-1415.3 of the San Joaquin County,Ordinance for Quarry Excavations that require slopes in excess of 50 feet to have terraces with a maximum distance between terraces of 50 feet. Although it has demonstrated that these slopes are stable,the project may require a variance from San Joaquin County. The periodic, localized fall of unsupported and loose rock from a slope, often referred to as raveling, is anticipated for temporary slopes during the project,but due to its isolated and localized occurrence, raveling is not considered to have a significant effect on mining activities. Failure of temporary slopes in areas of active mining could cause injury and damage but due to the nature of open pit aggregate mining, if a failure did occur in the vicinity of the active mining, it would affect a small number of workers within the immediate work area. A future landslide failure of the proposed permanent final slopes would occur within a relatively remote, reclaimed agricultural area,and would not directly expose people or property to substantial adverse effects ` from landslide hazards. Therefore, impacts related to slope stability would be less than significant. Mitigation: No mitigation is required. r Impact 4.7.2: Activities related to quarry operations that cause disturbance of surface soils would expose loose soil materials.Exposure of these soils to wind, rain,and concentrated runoff could cause localized erosion that could eventually damage the engineered earthen features.Erosion damage to these features could expose workers to injury and equipment to damage. This would be a less-than-significant impact. RMC Pacific Vernalis Quarry Mining and Reclamation Project 4.7-19 ESA/203015 Draft Environmental Impact Report May 2006 r