This paper discusses the probabilistic approach in landfill veneer cover design as well as the impact of variability associated with the design parameters. A framework for the reliability based design optimization methodology as reported in the literature is considered. Conventional deterministic design uses a factor of safety approach that do not cater for these uncertainties that arise due to heterogeneity of Municipal Solid Waste (MSW). The formulation considers a two-part wedge mechanism with the soil-geosynthetic interface acting as the plane of weakness. Random variables considered in the present study are unit weight, cohesion, and friction angle of the cover soil, adhesion between cover soil of active wedge and geosynthetic, and long term design strength of the reinforcement. Generally the long term design strength of the reinforcement (TD) can be derived from the ultimate value of geosynthetic reinforcement strength by applying reduction factors for chemical/biological degradation, creep, and installation damage. As opposed to the use of conventional reduction factors, in the present contribution, the geosynthetic force required to stabilize the cover soils for the stability is treated as random variable. The mean value of required geosynthetic force is computed for different coefficients of variation of soil-geosynthetic interaction coefficient and ultimate tensile strength of the geosynthetic reinforcement. © ASCE 2015.