Evaluating the environmental impact of stone columns on clay barrier liners in landfills

Abstract

The use of stone columns as a ground improvement technique in landfill sites has gained significant attention due to their potential to enhance stability, reduce settlement, and facilitate efficient drainage within the clay barrier layer. This study examines the performance of stone columns placed beneath a clay barrier in a controlled landfill environment. A laboratory-based physical experiment was conducted using two lysimeters filled with organic waste to simulate landfill conditions, with continuous monitoring over 5 months. This research specifically aims to evaluate the effectiveness of stone columns in controlling settlement, optimizing drainage, and preserving liner integrity under waste accumulation and structural loading. The experimental setup involved the installation of 2.5 cm diameter stone columns at a spacing of 7.5 cm (3D), with a length-to-diameter ratio (L/D) of 8 key parameters—including moisture content, temperature, liner pressure, total dissolved solids (TDS), pH, and settlement—were systematically recorded using embedded sensors. Additionally, a structural load was applied to assess its influence on the soil mass beneath the barrier. The findings indicate that stone columns significantly enhance landfill stability by improving drainage efficiency, maintaining consistent pressure, regulating temperature variations, reducing settlement, minimizing TDS accumulation, and stabilizing pH levels. These results underscore the viability of stone columns as an effective long-term solution for improving the performance and containment efficiency of landfill liners.