118 even recorded, prompting interventions and oversight by the OEFA due to uncontrolled discharges from mine shafts, of which there were 1,464. • Acid drainage from mine shafts and tailings ponds threatened the biodiversity of the surrounding Andean ecosystem. • The Pushaquilca liabilities were classified as high and very high risk to health due to the potential use of contaminated water, indirect exposure to mining effluents, and the presence of hazardous waste near populated areas. • Some liabilities featured steep, rocky slopes located in areas that were very difficult to access geographically. 2.3 Solution • Reprofiling and shaping of stable slopes. • Removal and controlled relocation of unstable materials (> 60,000 m³ of mine waste). • Diversion and controlled management of surface water via concrete-lined channels. • Landscape restoration through revegetation with native species capable of stabilizing the surface of the capping layer across more than 17ha. • Preventing the generation of acid drainage through geosynthetic sealing to control oxidation reactions, reduce contaminating effluents, and improve the system’s chemical stability; details regarding geosynthetic capping will follow. 2.4 Mining waste management facilities 2.4.1 Tailing pond The 5038 Tailings pond is located at the foot of a gently rolling hillside with a low slope. It has a maximum height of 8.3 m, a tailings thickness of approximately 5.50 m, and a layer of low-permeability clay material approximately 0.30 m thick. The bedrock is located at a depth of 6 m. The 5038 Tailings pond is classified according to the Unified Soil Classification System (USCS) as low plasticity silt (ML), very stiff, with a moisture content varying between approximately 18 and 28%. The final geometric configuration of the tailings deposit will have the following characteristics: • Bench height: 7 m. • Inter-bench slope: 3H:1V. • Disposal of sediments from Tailings Pond 1464, Cut 5035, and material from the affected area below Cut 5036. Geochemical Stability Geochemical stability was achieved by covering the tailings characterized as acidity generators, which was then revegetated to blend in with the surrounding landscape. To this end, Type C1 cover will be applied to the flat area and Type C3 cover to the slopes. Revegetation consisted of planting native species on the topsoil by transplanting
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