122 3.1 Problem • Stricter Brazilian regulatory requirements for the stability and environmental control of landfills (ABNT NBR 13028:2024 and ABNT NBR 13029:2024). • Technical and economic limitations of traditional solutions based solely on natural soil. • The need to reduce environmental impacts, the consumption of natural materials, and associated emissions. 3.2 Solution • The solution adopted for capping the waste pile was a multi-layer geosynthetic cover system, designed to waterproof, drain, stabilize, and protect the waste body, replacing traditional covers based exclusively on natural soil. 3.3 Description of the solution using geosynthetics To reduce the impacts described above, the use of geosynthetics placed on top of the tailings was proposed, with the configuration shown in Figure 12. Some relevant data on the closure: the closure cover was 0.30 m, slope height 10 m, slope ratio 3H:1V. Figure 12 - Typical section using geosynthetics. 3.4 Coverage Installation Procedure. The construction process schedule follows the structure shown in Figure 13. As a first step, the surface of the material to be covered was shaped and levelled. Next, a layer of nonwoven geotextile was installed on top of it. After this stage, the HDPE geomembrane was installed in accordance with the requirements of ABNT NBR 16.199:2020, ensuring its performance. With the waterproofing properly installed, the draining geocomposite layer was applied throughout the project area. Considering the large area, some of these steps were performed simultaneously on different work fronts to maintain operational efficiency, as shown in Figure 13.
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