Susceptibilidad de contaminación de las aguas subterráneas por el lixiviado generado en el relleno de Normandía, Santa Cruz – Bolivia.Tesis de Maestría.

Abstract

This thesis evaluates the susceptibility of groundwater contamination caused by leachate produced at the Normandía municipal landfill, located in the city of Santa Cruz, Bolivia. Groundwater beneath and around landfills is highly vulnerable to contamination due to the infiltration of leachate rich in organic matter, inorganic ions, and trace contaminants. The degree of impact depends on the leachate load, geological conditions, soil permeability, and groundwater flow direction. The study integrates field surveys, hydrogeochemical analysis, and hydrogeological characterization to assess the contamination potential of the unconfined aquifer underlying the landfill. Analytical results from 38 wells and piezometers reveal spatial variations in major ions (Cl⁻, NO₃⁻, SO₄²⁻), heavy metals, and organic indicators (BOD₅, COD), showing concentration peaks downgradient from the waste disposal zone. A combined approach involving hydrogeological mapping, flow direction analysis, and leachate plume delineation indicates that the aquifer exhibits medium to high vulnerability, particularly during the rainy season when infiltration increases. The study also applies statistical and geochemical tools (ion ratios, saturation indices, Piper diagrams) to differentiate natural hydrochemical signatures from contamination-induced anomalies. Findings demonstrate an upward trend in parameters such as electrical conductivity, chloride, nitrate, ammonium, BOD₅, and COD, confirming the influence of leachate infiltration. The hydrochemical facies identified downstream show a transition from calcium bicarbonate waters to more mineralized sodium-chloride and mixed-ion facies, reflecting anthropogenic alteration. This research provides one of the first scientific assessments of landfill-induced groundwater contamination in Bolivia and offers recommendations for monitoring, risk mitigation, and landfill management, including the need for improved leachate control, impermeabilization, and long-term aquifer surveillance.