Kettleman Hills Waste Landfill Slope Failure. II: Stability Analyses

Analyses were made to determine the cause of a stability failure of a 90 ft high, 15 acre hazardous waste landfill in which lateral displacements of up to 35 ft and vertical settlements of up to 14 ft were measured. The failure developed by sliding along interfaces within the composite geosynthetic‐compacted‐clay liner system beneath the waste fill. The shear resistances of the different interfaces in the liner system were determined by direct shear and pullout tests as described in a companion paper (Mitchell et al. 1990). Conventional two‐dimensional (2D) stability analyses of representative cross sections and three‐dimensional (3D) analyses of the overall waste fill and liner configuration are described. Each type of analysis was applied to two cases: (1) The “Probable Minimum Clay/Liner Wetting Case,” in which shear along a wetted HDPE liner/compacted clay interface was assumed to occur only over a small area of the base; and (2) the “Full‐Base‐Wetting Case,” in which the HDPE liner/compacted clay lin...