Five years of monitoring the swampy forest system: a pilot project for acid mine drainage treatment to achieve threshold value

Abstract This research evaluated the effectiveness of the swampy forest system, a unique and cost-effective approach developed based on a conventional method for acid mine drainage treatment at the Jorong coal mine in South Kalimantan, Indonesia. The conventional method uses lime for acid neutralization and is often considered expensive. Acid mine drainage, with its high acidity and heavy metal contents, must be mitigated to achieve threshold values before being released into public waters. This research aimed to determine whether the swampy forest system pilot project, implemented in 2019, had sustainable and proper operations. As mandated by applicable regulations, quarterly observations of seven threshold parameters before and after acid mine drainage were conducted between 2019 and 2024. The observations revealed that the swampy forest system could change the parameter values to achieve the threshold value within five years of operations, demonstrating its exceptional long-term sustainability. Conclusively, this system is viable for natural application at a low cost at the closure stage of the abandoned mine.