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Non-Water Release Corrective Action Plan North County Recycling Center and Sanitary Landfill Review of the interface friction values (Table 2) indicate that the most critical interface is between the geocomposite and the 60 mil double-sided textured HDPE. To evaluate the stability of the proposed landfill cover system, a stability analysis was performed for the landfill slopes at an inclination of 3:1 (horizontal to vertical). The analysis utilized the infinite slope method using the soil parameters presented in Table 2. The analysis assumed a potential failure plane through the most critical interface on the slope. The yield acceleration (ky) was calculated for the slope cover configuration. The calculations are presented in Figure B-3 (Appendix B) and summarized in the following Table 5: TABLE 5-COVER SYSTEM SLOPE STABILITY RESULTS FIGURE NO. Ky Failure along most critical slope cover interface B-3 0.158 Based on the yield acceleration value provided above, permanent seismic displacement calculations (Table B-2, Appendix B) were performed for the cover system in accordance with the procedures described above. The results of the calculations indicate less than 1 inch of permanent dynamic displacement under the loading of a PGA of 0.158. which is greater than the MCE design event. In accordance with CalRecycle's BMPs, 2010, Table 2, page 5, this magnitude of displacement is considered de minimus for ground motion and the cost for corrective action is not required. Based on our calculations, significant impacts resulting from dynamic displacement of the final cover under loading greater than the predicted MCE event are considered outside of the definition of a reasonably foreseeable impact. 4.1.6 Summary of Impacts from Seismic Hazards In summary, the potential for impacts to the NCRCSL from ground rupture, seiche, tsunami, liquefaction/ dynamic settlement, or refuse/cover system slope failure resulting from the design MCE is considered negligible and outside the definition of a reasonably foreseeable impact. 4.2 Precipitation Impacts Storms causing damage to the cover, exposure of waste, clogging of the drainage system, erosion or failure of slopes, are all possible due to excessive amounts of water. Therefore, excessive precipitation is a foreseeable casual event that can affect a landfill. Landfills are required to maintain systems to control run-on and run-off due to precipitation throughout the active and post-closure period. The standard for Class III Landfills, such as the NCRCSL, is to design for a 100-year, 24-hour storm event, which is defined as a one percent chance of occurring in any one given year (1/100 =0.01= 1%). 2013.A135 I N:\San Joaquin\North County\Non-Water Release CAP\Final Report\North County_NWCAP_Report_Final.docx July 2014,Rev.0 10