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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 6 October 2024 analysis are presented in Appendix A. 4.1.1 Impacts from Ground Rupture Seismically-induced ground rupture occurs when a fault moves during an earthquake. The nearest active fault is approximately 30 miles from the site. Accordingly, there is no reasonable expectation that ground rupture could occur at the landfill site because of the distance to the nearest active fault. Therefore, this is not a reasonably foreseeable impact at this site. 4.1.2 Impacts from Seiches A seiche is a seismically-induced wave on a restricted water body such as a bay, harbor, lagoon, or lake. The site is within 9.6 miles of the Camanche Reservoir, 16.3 miles from New Hogan Lake, and 18.9 miles from the Salt Spring Valley Reservoir and not within the drainages from these sources of water. Accordingly, at these distances and locations, an impact from a seiche is extremely unlikely, and outside the definition of a reasonably foreseeable impact. 4.1.3 Impacts from Tsunamis A tsunami is an oceanic wave or series of waves produced by an undersea or near-shore earthquake, landslide, or volcanic eruption. The NCRCSL is located approximately 65 miles from the Pacific Ocean (San Francisco Bay) at an elevation of 110 feet above mean sea level. As a result, and based on maps by the California Emergency Management Agency (Cal EMA, 2009), impacts from a tsunami are considered extremely unlikely, and outside the definition of a reasonably foreseeable impact. 4.1.4 Impacts from Liquefaction and Associated Dynamic Settlement Liquefaction and dynamic settlement of soils can be caused by strong vibratory motions that occur during an earthquake resulting in a total loss of shear strength in the affected soil layer, thereby causing the soil to flow as a liquid, sometimes causing excessive settlement and sand boils at the ground surface. Both research and historical data indicate that loose, saturated, granular soils generally within the upper 50 feet below the ground surface are susceptible to liquefaction and dynamic settlement, while the structure of silty clays and clays is generally not adversely affected by vibratory motion. Boring log data from EMCON (1987) and Kleinfelder (1986) were reviewed to evaluate subsurface conditions at the site. The majority of the foundation soils of the landfill are composed of dense to very dense sands and silty sand and very stiff to hard silts and clays. The SPT blow counts as reported on the boring logs were generally greater than 30 bpf. The depth to the water table below the base of the landfill ranges from 100 to 120 feet. In accordance with the Southern California Earthquake Center (SCEC, 1999), if the groundwater table is not within 50 feet of the existing ground surface or if the soil materials have a minimum SPT blow count of 30 bpf, an analysis for liquefaction effects is not necessary. Accordingly, based on a preliminary site screening for liquefaction, the potential for liquefaction (and