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1 <br /> 1 <br /> 1. INTRODUCTION <br /> 1 The Corral Hollow Landfill (Landfill) is a closed Class III landfill located in Northern <br /> California on the eastern edge of the Central Valley (37.6691 N, -121.4590 W). The <br /> Landfill is located approximately 5 miles southwest of Tracy, California on the eastern <br /> 1 margin of the Diablo Range Mountains. This report presents the results of a stability <br /> analysis carried out to verify the stability of the soil and geosynthetic cover that has been <br /> designed to cover waste that is currently residing outside the permitted waste footprint. <br /> 1 1.1 Project Understanding <br /> San Joaquin County has enlisted the services of Shaw Environmental, Inc. to design a <br /> final landfill cap extension to cover waste that was discovered outside the currently <br /> closed and capped landfill. The existing landfill cap consists of a soil foundation layer, a <br /> 1 one foot low permeability soil layer, and an approximately one foot vegetative soil layer. <br /> Expansion of the final cover to incorporate the waste currently residing outside the <br /> existing closure area will utilize a soil and geosynthetic lined cover. The cap extension <br /> 1 design utilizes an impermeable geomembrane overlain by a geocomposite drainage net, <br /> an earthfrll layer, and a vegetation layer. The maximum slope for the geosynthetic lined <br /> portion of the cover will be 3:1 (H:V), with the maximum height of the 3:1 slopes being <br /> 1 approximately eight feet. The maximum height of the 3:1 slopes will be on the north side <br /> of the landfill access road between approximate stations 5+50 and 10+50, reference <br /> Figure 1. It is anticipated that the 3:1 geosynthetic lined slopes will pose the most <br /> significant risk for soil veneer failure and will therefore be the focus of this stability <br /> report. <br /> 1 2. DESIGN CRITERIA AND METHODOLOGY <br /> 2.1 Design Criteria <br /> 1 Stability analyses have been performed for both static and seismic conditions. Because <br /> the Landfill is a Class III facility, the seismic slope stability has been performed using <br /> 1 ground motions corresponding to the maximum probable earthquake (MPE) as required <br /> by Title 27 of the California Code of Regulations (Title 27 CCR). Shaw Environmental, <br /> Inc. (Shaw) developed the MPE and corresponding ground motions based on a site- <br /> 1 specific seismic characterization,reference Attachment 1. <br /> 2.1.1 Static Design Criteria <br /> 1 Title 27 of CCR does not specify a minimum factor of safety requirement for slope <br /> stability under static conditions. However, traditional geotechnical practice typically <br /> requires a static factor of safety of 1.5 for the stability of permanent slopes. Accordingly, <br /> 1 a static factor of safety of 1.5 is considered acceptable for global slope stability under <br /> static conditions. <br /> 1 2.1.2 Seismic Design Criteria <br /> Title 27 CCR requires that Class III landfills be designed to resist a peak ground <br /> 1 acceleration corresponding to the MPE that the site is anticipated to experience. The <br /> Slope Stability Analysis Corral Hollow Landfill 41512012 <br /> 1 2 <br />