Clay-Modified Laterite Soil as Low-Hydraulic Conductivity Liner Material for Tailings Dam Construction

Abstract

The economic hardship in many developing countries, coupled with rising global demand for gold, has led to a significant increase in small-scale gold mining activities. Tailings dams are commonly used to store mining waste; however, conventional geomembrane liners, though effective, are often too expensive for small-scale operations. The increasing volume of tailings generated poses a growing risk of groundwater contamination, necessitating cost-effective and reliable alternatives. This study evaluates the suitability of clay-modified laterite soils as an economical liner material for tailings dams. Natural clay, laterite, and their blends were characterised through physical, hydraulic, chemical, and mineralogical tests. Results indicate that increasing clay content enhances fine fraction and plasticity while reducing maximum dry density. The hydraulic conductivity of laterite–clay blends established practical design thresholds (30–40% clay content) required to meet international liner requirements (≤ 1 × 10⁻⁹ m/s), depending on the particle gradation of the laterite soil. An empirical model developed to predict hydraulic conductivity from basic soil properties achieved a root-mean-square error of about 0.8, demonstrating good predictive capability. This study introduces a predictive framework and establishes optimal blending thresholds for clay-laterite liners tailored to artisanal mining applications.

Keywords: Laterite; Clay liners; Tailings dam; hydraulic conductivity; Fractal dimension.