Utilizing Acid Mine Drainage (AMD) Sludge in Reclamation

Acid mine drainage (AMD) treatment produces large volumes of metal-rich hydroxide sludge that is commonly stored or disposed of at substantial cost. Repurposing this material as a soil amendment could reduce disposal burdens and support reclamation of abandoned mine lands. This study evaluated AMD sludge as a soil amendment for vegetation establishment in field plots in Monongalia County, West Virginia, USA. Five treatments were tested with three replicates each: 100% topsoil (control); 25%, 50%, and 75% AMD sludge blended with topsoil; and 100% AMD sludge. Plots were established in fall 2022, reestablished in spring 2023, and monitored for ground cover, soil moisture, soil temperature, and electrical conductivity. Biomass and soil chemistry were analyzed at the end of monitoring. The 100% AMD treatment remained below the 70% ground-cover benchmark and did not support adequate vegetation establishment. In contrast, the 25% and 50% AMD treatments reached and maintained the benchmark during Phase 2 and did not differ significantly from the topsoil control at the end of the study. The 75% AMD treatment also had final ground cover comparable to the control but performed less consistently. The 100% AMD treatment retained more moisture, whereas electrical conductivity, soil temperature, and biomass did not differ significantly among treatments. Soil pH remained near neutral, and phosphorus was lower in AMD-amended treatments. Sludge composition varied substantially among samples, demonstrating the need for representative characterization before land application. Overall, AMD sludge shows potential as a partial soil amendment when blended with topsoil, particularly at lower application rates.