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(GCL) or geomembrane materials and geotextile materials. The analyses <br /> considered a variety of material interfaces that may exist in any planned cover <br /> configuration. Based on the results of the analyses, a suite of acceptable shear <br /> strengths for geosynthetic liner material interfaces was identified. While the GCL <br /> may be used in place of a compacted clay layer, its internal shear strength when <br /> hydrated is relatively low, and an additional 40-mil HDPE geomembrane layer <br /> could be required if a GCL is employed in the cover design. A VFPE <br /> geomembrane is proposed for the barrier layer of the Forward Landfill final <br /> cover. The seismic stability analyses of the proposed refuse configuration <br /> indicate that seismic displacements under Maximum Credible Earthquake (MCE) <br /> loads will be negligible. <br /> The slope stability analyses also assessed the integrity of the final cover system <br /> under both static and seismic loads. The analyses indicate that the interface <br /> between the geomembrane and the overlying vegetative soil layer will be the <br /> critical surface, but that a factor of safety of 1.5 can be achieved so long as a <br /> drainage layer is placed between the geomembrane and the overlying soils. The <br /> seismic stability analyses also indicate that the earth-induced displacement of the <br /> ANIL landfill cover will be negligible under MCE loads. <br /> 3.6 DRAINAGE AND EROSION CONTROL <br /> 3.6.1 DRAINAGE CONTROL SYSTEM DESIGN <br /> The primary function of the Forward Landfill drainage control system is to collect <br /> and convey storm water in a controlled manner to minimize erosion and <br /> infiltration of storm water into the refuse prism. The following sections describe <br /> the site hydrology and existing and proposed drainage control features. <br /> 3.6.1.1 HYDROLOGY <br /> A hydrology study for the proposed conditions at the site was conducted in <br /> accordance with 27 CCR, Section 20365. The objective of the hydrology study <br /> was to calculate storm water run-off for sizing and location information for the <br /> site's storm drain facilities at closure. <br /> The Rational Method hydrology utilizing guidelines set forth in the San Joaquin <br /> County hydrology manual was used to calculate peak discharge rates for a 24- <br /> Forward Landfill PCPCMP 3-8 <br /> L:\Allied\2000.193\Reports\FinaIPCPCMP:FL-sec3.doc:5/21/02 BRYAN A.STIRRAT 6 ASSOCIATES <br />