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Non-Water Release Corrective Action Plan North County Recycling Center and Sanitary Landfill AU24.1294.00 | Non-Water Release Corrective Action Plan Update 7 October 2024 associated dynamic settlement) at the site is low. Accordingly, based on site-specific seismic design parameters and foundation materials strength characteristics, impacts resulting from liquefaction and associated dynamic settlement are considered negligible, and outside of the definition of a reasonably foreseeable impact. 4.1.5 Impacts from Potential Slope Failure 4.1.5.1 Slope Stability Analysis To satisfy the requirements of CalRecycle’s BMPs, the final configuration of the landfill prism and cover slopes were evaluated for dynamic stability by using a horizontal PGA of 0.15g (which is greater than the predicted MCE). The Excavation Plan from Shaw (2010), the liner/cover site descriptions from Shaw (2007), and the groundwater contour map from CB&I (2013) were used as the basis to evaluate the dynamic stability of the existing landfill slopes. An evaluation of the static stability of the site slopes was not performed because it is not considered necessary for the dynamic analysis of the site per the CalRecycle guidelines. Groundwater levels are a minimum of 100 feet below the bottom of the waste and thus, groundwater was not considered in the stability analysis. Two cross sections were prepared to evaluate landfill refuse prism slope stability for the ultimate build-out landfill configuration (see cross section locations on Figure 2). The two chosen cross section locations were based on the cross section locations with the lowest factor of safety of the six cross sections presented in Shaw (2009). The cross section locations follow: • Cross section A-A’ was generated in the eastern portion of the landfill through the highest proposed portion of the landfill slope in the area of the shallowest landfill base. • Cross section B-B’ was prepared through the southern portion of the landfill in the area of the highest landfill slope. 4.1.5.2 Geotechnical Parameters The soil materials existing and proposed at the site include: native foundation materials, cover soils, geosynthetic liner/slope materials, drainage materials, and municipal solid waste (MSW) fill. All the landfill modules are lined with geomembrane (HDPE) liners. Geotechnical parameters required for analysis include unit weight and shear strength parameters (angle of friction and cohesion). Strength parameters for the MSW are based on published information by Kavazanjian et. al., (1995). The shear strength of the slope and base liners was obtained from Shaw (2009). The native alluvium/formational soils were set as impenetrable bedrock to force the failure surface through the overlying weaker geosynthetic interfaces. The strength of the proposed cover soils and geosynthetics was estimated from review of the referenced boring logs from the site; references presented in Section 8.0, Koerner