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Containment Systems Module 1 (previously designated "Modules 1 &2") were excavated to a depth of approximately 88 feet mean sea level (MSL). This Module is lined with a 60 -mil high-density polyethylene (HDPE) geomembrane which exceeded the regulatory requirements in force at that time, but which does not meet the requirements of CCR Title 27 and RCRA Subtitle D, enacted since that time. Leachate is collected in a sump and pumped to a 3,000 -gallon storage tank. Module 3 was constructed in 1995, excavated to a depth of approximately 88 ft MSL. The base of this Module is composed of a geocomposite clay layer (GCL) under a 60 -mil HDPE geomembrane in conformance with CCR Title 27 and RCRA Subtitle D. Leachate is collected in a sump and pumped to the same 3,000 gallon storage tank as Module 1. The interface between Modules 1 and 3 consists of an anchor trench/berm constructed to an elevation of 96 ft MSL. Module 4 was constructed in 2003, excavated to a depth of 60 ft MSL. The base of this Module is composed of a geocomposite clay layer (GCL) under a 60 -mil HDPE geomembrane in conformance with CCR Title 27 and RCRA Subtitle D. Leachate is collected in a sump and pumped to a 10,000 gallon storage tank or directly applied to the module. Leachate collected in tanks are returned to the landfill in accordance with the Waste Discharge Requirements (WDRs) issued by the Regional Water Quality Control Board (RWQCB). In accordance with the WDRs, LFG collection trenches are installed in the first refuse lift of each new module. LFG is collected from the LCRS of Modules 1 and 3 to enhance collection of LFG near the landfill liner. '• ■ A'0 1• The "foreseeable release" from the NCRC&SL is based on the containment features now in place and the history of compliance at the site. The landfill is completely lined with geomembranes and provided with leachate collection and recovery systems. This level of containment reduces both the chance of contaminant releases due to either leachate or landfill gas. Since the landfill is located in a semi -arid environment (average annual rainfall less than 20 inches per year), leachate accumulation resulting in an eventual release to groundwater is not as likely as the migration of landfill gas through penetrations in the base liner. A major release of leachate could only occur if the penetration fell within the areas of the base liner where leachate flow is concentrated and the chance of developing a hydraulic head (standing leachate) is increased. Conversely, landfill gas follows pressure gradients and will flow through penetrations regardless of location of the penetration on the base liner. Corrective Action Financial Assurance Cost Estimate 3 September 30, 2008 North County Recycling Center and Sanitary Landfill Public Works/Solid Waste Div.