This study concerns the feedback of a synthetic rubber geomembrane EPDM that was installed 12 years ago for the landfill cell cover of Lann Hir. An inspection visit has been organized to assess the condition of the geomembrane and sealing details. Part of the covering soil has been removed to allow visual inspection and take samples of the geomembrane that were subjected to analysis. The publication presents the Lann Hir landfill, the specificities of installing an EPDM geomembrane landfill cover and the test results showing that twelve years after its installation, the mechanical characteristics of the EPDM geomembrane and its seams are almost unchanged.