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Control aspects of underground coal gasification: LLL investigations of ground-water and subsidence effects. [Hoe Creek I and II]

Conference ·
OSTI ID:6575409

Our investigations are designed to evaluate some of the environmental implications of in situ coal gasification, and to identify appropriate environmental controls. Changes in ground-water quality and the possible effects of subsidence and ground movement induced by the underground gasification cavity represent significant environmental concerns associated with the in situ gasification process. We have measured these effects at the site of two in situ coal gasification experiments conducted in northeastern Wyoming by the Lawrence Livermore Laboratory. Our measurements of ground-water quality in the vicinity of the gasification experiments indicate that the reaction products, such as ash and some coal tars, that remain underground following gasification, are a potential source of localized ground-water contamination. However, the concentration of important contaminants, such as phenols, shows a significant decrease due to adsorption by the surrounding coal. Complementary laboratory measurements are providing detailed information concerning this adsorption process. We have also conducted laboratory and field measurements, in conjunction with modeling studies, to evaluate the effects of subsidence phenomena. Data from subsurface geotechnical instruments installed at the second gasification experiment, as well as measurements of ground-water levels, indicate that roof collapse connected the gasification cavity with overlying aquifers. The environmental implications of this interconnection are being investigated. Our results suggest that hydrogeological site-selection criteria may be of considerable environmental importance in choosing locations for commercial-scale operations.

Research Organization:
California Univ., Livermore (USA). Lawrence Livermore Lab.
DOE Contract Number:
W-7405-ENG-48
OSTI ID:
6575409
Report Number(s):
UCRL-81887; CONF-781109-3
Country of Publication:
United States
Language:
English