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l ' NSC clamped to the top box. The membrane and soil were Ioaded into the shear device under the normal stress used in each test. The normal stress was applied by regulated air and left on for a period of 24 hours prior to shearing. The soil for test series 2 was to be compacted to a relative compaction of 90% at a water content of 2 to 4 percent above optimum (modified Proctor, ASTM D 1557). A dry density and moisture content of 107.01 pcf and 15.24% respectively, were used. The profile for these tests was from top to bottom: • NSC 60-mil single sided textured HDPE geomembrane (textured side against GCL) • Bentofix NW GCL (non-woven geotextile on both sides) • compacted site subgrade soil. Each GCL specimen was saturated under a normal stress of 100 psf for 24 hours prior to placing the sample in the direct shear device. The soil was then compacted into the bottom box, the GCL was placed on top of the soil and the geomembrane (clamped to the upper box) was placed on top of the GCL. The normal stress was applied and the shear box was hydrated for 24 hours before shearing. Shear Testing The interface direct shear tests were performed in general accordance with the ASTM Standard Test Method 5321, Determining the Coefficient of Soil and Geosynthetic or Geosynthetic and Geosynthetic Friction by the Direct Shear Method. The test speed for all tests was 0.04 in/min. The displacement was 2 inches. Observations Test Series l Normal Stress Shear Plane Observations Sheared pieces of soil were left 4000 psf Internal in the soil on the geomembrane; soil was hanging over rear of bottom box. Sheared pieces of soil were left 8000 psf Internal in the soil on the geomembrane; soil was hanging over rear of bottom box. Sheared pieces of soil were left 13000 psf Internal in the soil on the geomembrane; soil was hanging over rear of bottom box.