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but are approximately 30 to 40 feet below amsl. According to the San Joaquin <br /> County Flood Control District, the historic high groundwater elevation is <br /> approximately 10 feet below amsl. If the historic high were to occur, a waste to <br /> groundwater separation of approximately 17 feet would be maintained. Given the <br /> effectiveness of the base lining system and the minimum 17-foot separation <br /> between the base of the WMU and groundwater, the lowered base grades exceed <br /> the technical and regulatory objectives for groundwater and waste separation. <br /> 5.2.2 LINER AND LCRS COMPONENTS <br /> The liner and LCRS system for the existing Forward Landfill were previously <br /> described in Section 4.1.1. A base liner-and slope liner system are presented <br /> below for the future Forw-ard,lamffill. Theemsling..Austin Road Landfilldoesnot <br /> have a liner/LCRS system. An intermediate liner system is required over the <br /> existing refuse fill to separate Class III from Class II waste. That system is also <br /> described herein. <br /> 5.2.2.1 BASE LINER SYSTEM <br /> L The base liner system is designed in accordance with 27 CCR, Section 20330 <br /> requirements for a Class II liner system applicable to the Forward Landfill. The <br /> base liner components for the Forward Landfill consist of(from bottom to top) <br /> (see Details 1 and 4 on Drawing 6j <br /> • Prepared subgrade; <br /> • A 24-inch thick low-permeability soil (minimum permeability of 1 x 10'' <br /> cm/sec) or GCL; <br /> • A 60-mil high density polyethylene (HDPE) liner (textured); <br /> • A 12-ounce/square yard cushion geotextile(which=can be omitted provided <br /> the LCRS is sub-angular to rounded); <br /> • A 12-inch LCRS gravel layer; <br /> • An 8-ounce/square yard separator geotextile; and <br /> • A 12-inch thick protective cover soil layer. <br /> A leachate collection and recovery system, including leachate collection swales <br /> and LCRS pipes, collect leachate from the LCRS gravel layer. Spacing of LCRS <br /> lateral pipes and headers was determined by HELP2 leachate generation <br /> Forward Landfill JTD 5-2 <br /> L:\AII ied\2000.193\Reports\finaljtd:Sec-5.0:08/22/01 <br /> BRYAN A.STIRRAT 6 ASSOCIATES <br />