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strength requirement. Based on our experience,the required shear strength can be achieved with <br /> proper selection and testing of the geotextile cushion and textured HDPE geomembrane <br /> materials. -The interface shear strength shall be demonstrated using actual geotextile and <br /> geomembrane to be used in Module 4 liner construction, in the Contractor's product submittals, <br /> and shall be verified by conformance testing required in the QAM. <br /> 4.0-Recommendations <br /> To protect the 60-mil HDPE geomembrane from the proposed crushed rock, a 16-ozly& <br /> geotextile (non-woven, needle-punched) cushion shall be provided between the crushed rock and <br /> the geomembrane. <br /> The geotextile-textured HDPE geomembrane interface shall meet a minimum residual shear <br /> strength (measured at 3-inch displacement) defined by a friction angle of 10.5 degrees. In <br /> addition to the shear strength requirements previously specified in the construction <br /> specifications, the shear strength of the geotextile cushion-textured HDPE geomembrane <br /> interface shall be demonstrated and verified using direct shear testing (ASTM D5321) before <br /> installation of the liner system. The testing will be performed under: <br /> • Normal Stresses: 2,000, 4,000,and 8,000 psf <br /> • Strain Rate: 0.2-inch/minute <br /> • Minimum Displacement 3-inches <br /> • Saturation: Test under saturated conditions <br /> N:\s&cDP\2003\Prj\83\835608.3ap.doc <br /> (NCRCSL) <br /> 4 <br />