ARCHIVED REPORTS_1993_1 - Laserfiche WebLink

Home Browse Search

1 Slope stability analyses were performed on two slope cross sections, one with an inclination of 2:1 (horizontal to vertical), the other with an inclination of 1.5:1. Soil parameters were obtained from laboratory data. The slopes were analyzed for short term and long term stability. Long term analyses included a dry and a high ground water case under static load. Short term analyses included un -drained (end of construction) and earthquake loading cases. The calculated factors of safety were above the levels recommended by RGH in all cases except for the case of a 1.5:1 slope with high ground water. The analyses indicated that slopes with these conditions would be unstable. ENVIRONMENTAL IMPACTS AND MITIGATION MEASURES This section identifies and discusses the potentially significant environmental impacts which result from the effects of 'geologic hazard' on the development and operation of the Tracy Materials Recovery and Transfer Facility. Examples of geologic hazards can include: ground rupture due to faulting; ground shaking during earthquake; liquefaction; seismic settlement and differential compaction; landslides; ground subsidence (non -seismic) and collapsing or expansive soils. The analysis has been formulated on the basis of available information, using reasonable projections of the worst case consequences. For the purposes of this section, an environmental impact is defined as a change in the status of the existing physical conditions that would be affected by the proposed action or alternative. The effects can be direct (primary), which are caused by the project and occur at the same time and place, or indirect (secondary), which are caused by the project and are later in time or farther removed in distance, but are still reasonably foreseeable. Specific, detailed mitigation measures are proposed and described for all potentially significant environmental impacts. Where there is no feasible mitigation identifiable, or where proposed mitigation measures do not reduce the impact to a level of less -than -significant, the impact is considered to be a significant, unavoidable, adverse impact. Significance Criteria The California Environmental Quality Act (CEQA), Supplementary Document G, states that 'a project will normally have a signfcant effect on the environment if it will: conflict with adopted environmental plans and goals of the community where it is located; or expose people or structures to major geologic hazards. According to CEQA guidelines, geological -related impacts of project development would be considered to be significant if they could result in one or more of the following conditions: • Exposure of people to injury or structures to damage as a direct consequence of a geologic event. • The release of contaminants from the project into the environment due to the occurrence of a geologic event. • Substantial erosion or siltation of the area affected by the project. • Disruption or adverse effect on a paleontological site. Additional geological -related impacts that are commonly considered significant include: • Substantial changes in topography caused by the project. • Adverse effects on unique geologic or topographic features. ER -93-1 -60- (9-27-93)