The tailings from gold beneficiation can cause various negative impacts, necessitating measures to prevent their transport and environmental contamination. Geomembranes serve as hydraulic barriers in mining tailings reservoirs, thereby supporting the Sustainable Development Goals (SDGs). To ensure that the geomembrane effectively mitigates environmental impact, it is essential to study its durability when applied in the field. This article examines the long-term performance of an HDPE geomembrane exposed for 7 and 11 years at a gold mining tailing site in Brazil. Samples were exhumed from different locations at the dam, and their properties were evaluated. Non-parametric statistics were employed using the Kernel Density Estimator (KDE). For the 11-year-old geomembranes, the probability of the geomembrane reaching nominal failure in terms of tensile strength was 0.4%. The peel separation values exceeded the maximum allowable by the GRI GM13 standard. Although the geomembranes showed significant antioxidant depletion, suggesting they were close to or had already reached their residual stages, they approached nominal failure based on their stress crack resistance but did not rupture. The environmental analysis indicated no significant contamination in the area, corroborating that the geomembrane is fulfilling its function. The non-parametric methodology proved promising for durability analysis and could be applied to other engineering projects with geosynthetics, thereby adding reliability to decision-making in alignment with sustainable development.

Degradação de Geotêxteis Expostos às Intempéries/ Degradation of Geotextiles Exposed to Weather

Sistema de confinamento de resíduos empregando geotêxteis comparados a leito de drenagem para desaguamento de lodo de estação de tratamento de água / Waste containment system using geotextiles compared to drainage bed for dewatering sludge from water treatment plant

The long-term reliability of geomembranes is essential for maintaining environmental safety and protecting human health, particularly when applied in demanding environments such as mining. This study evaluates the long-term performance of a 2 mm high-density polyethylene (HDPE) geomembrane after 12 years at a gold mining tailings pond in Brazil. As built performance data were unavailable, so analyses were based on GRI GM13 standard. Three samples from various dam locations were analysed using the Kernel Density Estimator (KDE) for non-parametric statistical analysis. The geomembrane’s failure probability in terms of tensile strength was 19%, indicating an 81% success rate as a hydraulic barrier. The lowest stress crack resistance (SCR) among samples exceeded the 50% SCR of the GRI GM13 standard. Significant antioxidant depletion was noted in the Standard Oxidative Induction Time (Std-OIT) tests, down to 14% of the minimum GRI GM13 value, while the High-Pressure Oxidative Induction Time (HP-OIT) showed only slight depletion, down to 80% of the minimum GRI GM13 value. Environmental analysis revealed no significant contamination, confirming the geomembrane’s effectiveness.

In 2008, a 1.5 mm smooth high-density polyethylene (HDPE) geomembrane was applied as a lining over 800 m of a concrete water supply canal in southeaster Brazil. This study aims to enhance the understanding of geomembrane durability through a case study of a HDPE geomembrane after 10 years, comparing samples submerged in water with those exposed to weather. Mechanical parameters such as tensile strength, tear resistance, and puncture resistance were tested and compared to GRI GM13 standard. Submerged samples primarily faced mechanical damage risk from debris, while weather exposed samples suffered mainly from mechanical, thermal and UV degradation. Results indicated that all parameters for submerged samples exceeded GRI GM13 requirements. Conversely, weather exposed samples showed some variations from the values established by the GRI GM13 Standard. Of the 11 parameters tested, 7 met the GRI GM13 standards, including tensile strength and tear resistance in both machine (MD) and transverse (TD) directions, and puncture resistance. Only transverse elongation at break showed a 40% reduction in the minimum value of GRI GM13. Most of the parameters for the weather-exposed samples were within 80% of the results for the submerged samples, with the exceptions of the tensile strength and elongation at break-both in transverse direction-, which were within 50%.