The opening of a second tailings storage facility represented a critical threshold in the site's long-term mining plan. Since the new TSF required a water balance and containment concept independent of the existing facility, the panel layout, weld line density, and drainage corridors were designed from scratch. The use of textured HDPE geomembrane in the base and slope areas was determined according to friction parameters and slope stability calculations. The heavy rainfall windows brought by the tropical climate necessitated the modular planning of the installation schedule; the area deployed each day was secured against wind uplift by temporary anchoring and sandbags at the end of the shift. Weld quality control was completed with peel tests on extrusion seams, in addition to vacuum box and air channel tests. The project is still ongoing, and the cell is planned to be raised in stages in subsequent phases.