In order to understand the pollution process of underground coal gasification (UCG) and realize ultimate control, the possible processes of groundwater pollution were analyzed and typical pollutants were identified and several pollution control measures were proposed.Location selection in UCG has important effects on UCG stability control and groundwater pollution control and there are many factors for considering, such as coal reserves, coal seam conditions, geological structure, h ydrological conditions. Groundwater pollution is caused by the diffusion and penetration of contaminants generated by UCG processes towards surrounding strata and th e possible leaching of underground residue by natural groundwater flow after gasification.Typical organic pollutants includes phenols, benzene, minor components such as PAHs and heterocyclics.Inorganic pollutants involve a variety of hamful elements.The extent and concentration of the contaminants decrease over time and with the distance from the burn cavity since the adsorption function of coal and surrounding strata.Possible pollution contral measures include identifying a permanently, unsuita ble zone, setting a hydraulic barrier and pumping contaminated water out for surface disposal.Mitigation measures during gasification processes and groundwater reme diation after gasification are also proposed.
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