Environmental impacts of coal combustion residues

Coal combustion residues account for 90% of all fossil fuel combustion wastes produced in the USA. It is projected that by the year 2000 more than 150 million t of these materials will be produced in the USA each year. Presently, only about 20% of these wastes are utilized, with the remainder deposited in landfills or surface impoundments. This article reviews the information available concerning the environmental impacts associated with the disposed or utilization of coal combustion residues. The majority of the information available in the literature concerns the impacts of fly and bottom ashes; other coal combustion wastes have not received much attention.