Waste Management and Conceptual Monitoring Framework for Historical Tailings and Open-Pit Mines
Case Study of Tharsis-Lagunazo Mining District, SW Spain
Debbie Novalina Debbie Novalina Butar Butar (TU Delft - Civil Engineering & Geosciences)
F.S. Desta – Mentor (TU Delft - Civil Engineering & Geosciences)
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Abstract
This study evaluates the environmental risks associated with the Tharsis-Lagunazo mining district located in the Iberian Pyrite Belt (IPB) of southwestern Spain. It primarily focuses on two key issues: acid mine drainage (AMD) and slope instability. The study proposes an integrated conceptual framework for waste management and monitoring. To achieve this, the study combines geological mapping, geochemical analysis, and hydrogeological interpretation with geotechnical slope assessments and satellite-based remote sensing. This multi-method approach effectively identifies sources of hazards, transport pathways, and sensitive environmental receptors. In addition, a multi-criteria decision analysis (MCDA) was utilized to rank critical variables for effective monitoring and site management.
Results indicate that hydrological dynamics and water chemistry are the primary controls on environmental risk. AMD generation and transport are strongly influenced by rainfall seasonality, evaporation rates, and drainage system connectivity. Key chemical indicators of AMD intensity include pH, electrical conductivity, and concentrations of Fe, Cu, and Zn. Both the Lagunazo and Mina Tharsis sites contain multiple hazard sources, such as tailings, seepage zones, and acidic pit lakes that are directly connected to downstream reservoirs. The highest contamination risks occur during rainfall events following dry periods.
Geotechnical risks are site-specific in the study area. They are mostly found at steep, weathered pit walls at Tharsis, which increase erosion and sediment delivery, while fine-grained, low-permeability tailings at Lagunazo facilitate water ponding and prolonged chemical reactions. Remote sensing proved effective for spatial screening, enabling delineation of zones affected by AMD. This integrated framework establishes clear priorities for monitoring and supports targeted rehabilitation and risk-reduction measures for abandoned mining districts, such as in Tharsis-Lagunazo.