Commonly, tailings impoundment does not have an impermeable liner system, then if seepage flow contains acid water or precipitated metals from tailings, this can cause consequences or serious impacts in the ecosystem. The magnitude of the impact depends on the acidity generation degree or metal concentration that the tailings may have and the amount of seepage flow. In those cases, a geomembrane liner system is needed. This research is developed based on a project where the geosynthetics selection is important because the large area of the tailings impoundment to be lined and also because the chosen geosynthetics has to meet technical restrictions of the project, such as differential settlements. Nowadays, there are a variety of geomembrane to be used as liner system for tailings impoundment, for example HDPE, LLDPE, PVC and FPP. When the project needs to choose one geomembrane it must be done in order of geosynthetic assessment (cost and technical aspects). The objective of this research is to evaluate and select the best geomembrane liner which reaches the requirements of a tailings impoundment located in the Peruvian Andes through the Choosing by advantages method (CBA method). This methodology consists on the possibility to separate the estimate cost from valuable attributes of each alternative. In the technical aspect, the geomembrane will be evaluated by their performance of differential settlements, and in the economic aspect by costs of supply and installation will be considered.