This webinar will focus on estimating the static and seismic deformations along the critical interface of a landfill bottom liner system using the software package FLAC. In particular, the construction, filling, and waste settlement are modeled to analyze the relative displacement between geosynthetic interfaces during static landfill operation. The calculated relative shear displacements of the geosynthetic interface are then compared to the Stark and Poppel (1994) recommendations to suggest design interface strength for future projects. Afterwards, recorded ground motions are applied to the model to estimate seismic deformations to understand liner system deformations in seismic areas. 1.0 PDH