Obtaining water quality permits for land application of biomass boiler ash

Land application of biomass fuelled boiler ash can save landfill space and return cations to the forest environment. However, environmental regulations throughout most of the U.S. do not specifically address application of biomass boiler ash to forest land. South Carolina Department of Health and Environmental Control (SCDHEC) treated bark boiler ash from International Paperʹs Georgetown, SC, mill as an experimental permit with a requirement of monitoring experimental applications to show it would have “no detrimental impact to the environment or public health”. An initial catchment study showed no evidence of leaching into either the watertable aquifer or outlet streams when ash was applied to moderately well-drained portions of two watersheds at a rate of 11 Mg/ha. Concentrations of elements in groundwater samples were well within state drinking water standards, often more than an order of magnitude below the standards. The second study was a replicated block experiment of ash application rates of 11, 22 and 44 Mg/ha. Ash application increased leaching significantly for potassium, calcium and sulfate, although concentration increases were modest (0.12–0.17 Mg/l for potassium, 0.36–0.89 mg/l for calcium and 1.92–3.08 mg/l for sulfate). Groundwater heavy metal concentrations were well below drinking water standards, even at the 44 Mg/ha rate.