Leaching of chromated copper arsenate (CCA)-treated wood in a simulated monofill and its potential impacts to landfill leachate.

The proper end-of-life management of chromated copper arsenate (CCA)-treated wood, which contains arsenic, copper, and chromium, is a concern to the solid waste management community. Landfills are often the final repository of this waste stream, and the impacts of CCA preservative metals on leachate quality are not well understood. Monofills are a type of landfill designed and operated to dispose a single waste type, such as ash, tires, mining waste, or wood. The feasibility of managing CCA-treated wood in monofills was examined using a simulated landfill (a leaching lysimeter) that contained a mix of new and weathered CCA-treated wood. The liquid to solid ratio (LS) reached in the experiment was 0.63:1. Arsenic, chromium, and copper leached from the lysimeter at average concentrations of 42 mg/L for arsenic, 9.4 mg/L for chromium, and 2.4 mg/L for copper. Complementary batch leaching studies using deionized water were performed on similar CCA-treated wood samples at LS of 5:1 and 10:1. When results from the lysimeter were compared to the batch test results, copper and chromium leachability appeared to be reduced in the lysimeter disposal environment. Of the three metals, arsenic leached to the greatest extent and was found to have the best correlation between the batch and the lysimeter experiments.