Review of the environmental impact of ground disposal of oil shale wastes

Waste disposal methods for the major types of extraction processes, the potential environmental impacts of waste disposal to the ground, mitigation of environmental effects, and further research needs of the oil shale industry are considered. Principal waste products of oil shale extraction constitute up to 125% of the original volume, and disposal may, therefore, affect vast land areas. Principal wastes scheduled for ground disposal include the waters produced during retorting and subsequently separated from the shale oil and the spent shales remaining after extraction. Retort waters contain relatively high concentrations of complex, soluble organic components and the spent shales contain potentially leachable salts and organic pyrolytic products. In addition, spent shales have erosion potential when disposed on the surface and considerable effort is being directed to shale management, emphasizing erosion control and shale as a growth medium, and revegetation methods for establishing salt- and drought-tolerant plant species.