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The lining system for the northeastern portion of WMU FU-04 incorporates the interim final cover for the former Austin Road Landfill. It consists of (from bottom to top): a two-foot foundation layer compacted to a minimum 90 percent relative compaction, a one-foot thick clay liner, and a one-foot thick vegetative layer. The overlying WMU ART-03 LCRS consists of(from bottom to top): an B- ounce nonwoven geotextile, a 0.5-foot thick layer of granular drainage material, another 8 ounce nonwoven geotextile, and a 1-foot thick protective operations layer. Material properties used in the stability analyses were based on actual test data from previous WMUs constructed at the site and a review of published values in the literature. The clay liner in the interim final cover was considered to be the weakest plane in the lining and LCRS system. Although the vegetative layer and protective operations layer are constructed at approximately 85 percent compaction rather than the 90 percent compaction of the clay liner, the materials used in the construction of the protective operations layer and vegetative layer are slightly sandier and would have a similar or higher shear strength than the clay liner. The granular drainage material, even in contact with the nonwoven geotextile,will also have a higher shear strength than the clay liner. Although there is not existing shear strength information on the clay liner material alone, it was conservatively assumed that the clay liner had a similar shear strength to the HDPE geomembrane/clay liner interface shear tests previously conducted at the site. Interface shear strength laboratory testing was performed for the construction of the WMUs D-95, D-97, D-98, D-99, D-00, D-01, D-02, and FU-03 lining systems (CH2M HILL 1995b and 1997c, Vector 1999a and 1999b, EMCON/OWT 2000, Holdredge and Kull 2001, Vector 2002, Vector 2003). Table 3-1 presents the assumed material properties used in the stability analysis. FU-04 REPORT.DOC 3-5