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v • The lack of liquid phase component to the existing Austin Road release, • Superior site operations, • The extensive Construction Quality Assurance (CQA) protocols that have been and will be implemented to ensure the performance characteristics of the liner, • Existing and proposed site controls, and • Existing monitoring systems. 2.0 INHERENT PROTECTION F SINGLE COMPOSITE LINERS 2.1 General In the preamble to the federal Subtitle D municipal solid waste liner system regulations, it states that "The composite liner system is designed to be protective in all locations, including poor locations." In their November 9, 2000 memorandum, the CVRWQCB also indicated that single composite liner performace was adequate and in their response to inquiry by the CVRWQCB, the State Water Resourcess Control Board also indicated that a single composite liner should perform adequately. A composite liner system consistent with the State of California (Title 27) and Federal (Title 40) regulations governing minimum standards for composite liner system design and performance includes redundant and complementary systems to prevent landfill impacts to groundwater. The composite liner system should include two low - permeability layers that have complementary physical and hydraulic properties such as a High Density Polyethylene (HDPE) Flexible Membrane Liner (FML) overlying a two - foot thick Compacted Clay Liner (CCL). The combined performance of these elements is significantly better than the performance of either individual component alone. The low -permeability elements of the liner should be complemented by a laterally extensive drainage network referred to as the Leachate Collection and Removal System (LCRS) which will convey landfill -impacted liquids off of the low -permeability layers. This LCRS system further reduces the potential for leakage. The LCRS is typically covered with a geosynthetic filter fabric and at least one foot of clean soil, which further protects underlying layers from potential damage from landfall operations. A discussion of the individual elements of a typical composite liner system is presented below. "PENORY" To maintain its function over the active life of the landfill and the post -closure maintenance period, the HDPE component of a modern single composite liner system is manufactured according to strict specifications which result in a geomembrane that is extremely resistant to chemical degradation. In addition, over the last several years, the state-of-the-art in FML design, manufacturing and construction has advanced C:U000A481For»srd Composite Liner V3 .doA09119/02 IR Geologic Associates